Mac OS X forum: kernel panic on Mac Pro-need a fix, pronto!

Mac will not start up for longer than 45 sec w/o a kernel panic happening. It is a multi-user account workstation where one of the account owners no longer works here. The accounts that both he and I operate on are admins. Below are main details:

MacPro4,1
Quad-Core Intel Xeon, 2.66GHz, 8GB RAM, 3 active HDDs with one operating as a Time Machine backup drive.

Kernel Panic report:

Interval Since Last Panic Report: 996705 sec
Panics Since Last Report: 29
Anonymous UUID: 73ED422B-597F-4AE1-A71D-0ECFC0E55B7C

Wed Feb 16 08:05:59 2011
panic(cpu 0 caller 0x2dfbef): "vnode_rele_ext: vp 0x13b940c4 usecount -ve : -1. v_tag = 24, v_type = 1, v_flag = 84810."@/SourceCache/xnu/xnu-1504.9.26/bsd/vfs/vfs_subr.c:1669
Backtrace (CPU 0), Frame : Return Address (4 potential args on stack)
0x86793618 : 0x21b50c (0x5d4438 0x8679364c 0x223974 0x0)
0x86793668 : 0x2dfbef (0x59af88 0x13b940c4 0xffffffff 0x18)
0x867936b8 : 0x2dfe18 (0x13b940c4 0x0 0x0 0x0)
0x867936d8 : 0x12aef21 (0x13b940c4 0x18711e6c 0x21000001 0x186fad20)
0x867936f8 : 0x2f94ce (0x18711e00 0x10b40174 0x86793728 0x4a4051)
0x86793728 : 0x2df46b (0x1870a250 0x10b40174 0x0 0x2)
0x86793788 : 0x2df5ca (0x1870a250 0x1 0x0 0x29f54e)
0x867937d8 : 0x2e22d9 (0x0 0x823024 0x4c491d6b 0x0)
0x86793848 : 0x41c06f (0x0 0x34 0x867938bc 0x186c1554)
0x86793908 : 0x423901 (0xe4cb004 0x18654f08 0x86793f08 0x86793a48)
0x86793a78 : 0x2fbedb (0x86793a98 0x3 0x86793ac8 0x5823ca)
0x86793ac8 : 0x2d982a (0x18654f08 0x86793df4 0x86793f08 0x10b40174)
0x86793b58 : 0x2da65c (0x86793ddc 0x100 0x86793dfc 0x0)
0x86793c18 : 0x2e97d0 (0x86793ddc 0x0 0x0 0x0)
0x86793d88 : 0x2e9c13 (0x780290 0x1 0x0 0x0)
0x86793f48 : 0x2e9cac (0x780290 0x1 0x0 0x0)
0x86793f78 : 0x4f13be (0xf6ed540 0x10744368 0x10b400b4 0x1)
0x86793fc8 : 0x2a143d (0x10744364 0x0 0x10 0x0)
Kernel Extensions in backtrace (with dependencies):
com.apple.filesystems.ntfs(3.3)@0x129a000->0x12f9fff

BSD process name corresponding to current thread: mdworker

Mac OS version:
10J567

Kernel version:
Darwin Kernel Version 10.6.0: Wed Nov 10 18:13:17 PST 2010; root:xnu-1504.9.26~3/RELEASE_I386
System model name: MacPro4,1 (Mac-F221BEC8)

System uptime in nanoseconds: 176751715227
unloaded kexts:
com.apple.driver.AppleIntel8254XEthernet 2.1.1b7 (addr 0x1007000, size 0x118784) - last unloaded 164846170520
loaded kexts:
com.parallels.kext.prl_vnic 6.0 11828.615184
com.parallels.kext.prl_netbridge 6.0 11828.615184
com.parallels.kext.prl_usb_connect 6.0 11828.615184
com.intego.kext.VirusBarrier.AppBarrierKPI 10.6.9
com.parallels.kext.prl_hid_hook 6.0 11828.615184
com.intego.kext.VirusBarrierKPI 10.6.9
com.parallels.kext.prl_hypervisor 6.0 11828.615184
com.apple.driver.AppleHWSensor 1.9.3d0 - last loaded 58003127649
com.apple.driver.AppleTyMCEDriver 1.0.2d2
com.apple.driver.AGPM 100.12.19
com.apple.driver.AppleMikeyHIDDriver 1.2.0
com.apple.driver.AppleUpstreamUserClient 3.4.5
com.apple.driver.AppleMCCSControl 1.0.17
com.apple.driver.AppleMikeyDriver 1.9.9f12
com.apple.driver.AppleUSBDisplays 283
com.apple.driver.AppleHDA 1.9.9f12
com.apple.driver.AudioAUUC 1.13
com.apple.GeForce 6.2.6
com.apple.Dont_Steal_Mac_OS_X 7.0.0
com.apple.driver.AudioIPCDriver 1.1.6
com.apple.driver.AppleIntelNehalemProfile 11
com.apple.filesystems.autofs 2.1.0
com.apple.driver.ACPI_SMC_PlatformPlugin 4.5.0d5
com.apple.driver.AppleLPC 1.4.12
com.apple.filesystems.ntfs 3.3
com.apple.iokit.IOAHCIBlockStorage 1.6.3
com.apple.iokit.SCSITaskUserClient 2.6.5
com.apple.BootCache 31
com.apple.AppleFSCompression.AppleFSCompressionTypeZlib 1.0.0d1
com.apple.driver.AppleFWOHCI 4.7.1
com.apple.driver.AppleUSBHub 4.1.7
com.apple.driver.Intel82574L 2.1.4b1
com.apple.driver.AppleEFINVRAM 1.4.0
com.apple.driver.AppleAHCIPort 2.1.5
com.apple.driver.AppleUSBEHCI 4.1.7
com.apple.driver.AppleUSBUHCI 4.1.5
com.apple.driver.AppleRTC 1.3.1
com.apple.driver.AppleHPET 1.5
com.apple.driver.AppleACPIButtons 1.3.5
com.apple.driver.AppleSMBIOS 1.6
com.apple.driver.AppleACPIEC 1.3.5
com.apple.driver.AppleAPIC 1.4
com.apple.driver.AppleIntelCPUPowerManagementClient 105.13.0
com.apple.security.sandbox 1
com.apple.security.quarantine 0
com.apple.nke.applicationfirewall 2.1.11
com.apple.driver.AppleIntelCPUPowerManagement 105.13.0
com.apple.driver.AppleProfileReadCounterAction 17
com.apple.driver.AppleUSBAudio 2.7.6f4
com.apple.driver.DspFuncLib 1.9.9f12
com.apple.driver.AppleProfileTimestampAction 10
com.apple.driver.AppleProfileThreadInfoAction 14
com.apple.driver.AppleProfileRegisterStateAction 10
com.apple.driver.AppleProfileKEventAction 10
com.apple.driver.AppleProfileCallstackAction 20
com.apple.driver.AppleSMBusController 1.0.8d0
com.apple.nvidia.nv50hal 6.2.6
com.apple.NVDAResman 6.2.6
com.apple.iokit.IONDRVSupport 2.2
com.apple.iokit.IOFireWireIP 2.0.3
com.apple.iokit.IOSurface 74.2
com.apple.iokit.IOBluetoothSerialManager 2.3.8f7
com.apple.iokit.IOSerialFamily 10.0.3
com.apple.iokit.IOAudioFamily 1.8.0fc1
com.apple.kext.OSvKernDSPLib 1.3
com.apple.driver.AppleHDAController 1.9.9f12
com.apple.iokit.IOGraphicsFamily 2.2
com.apple.iokit.IOHDAFamily 1.9.9f12
com.apple.iokit.AppleProfileFamily 41
com.apple.driver.AppleSMC 3.1.0d3
com.apple.driver.IOPlatformPluginFamily 4.5.0d5
com.apple.driver.AppleSMBusPCI 1.0.8d0
com.apple.driver.AppleUSBHIDKeyboard 141
com.apple.driver.AppleHIDKeyboard 141
com.apple.iokit.IOUSBHIDDriver 4.1.5
com.apple.driver.BroadcomUSBBluetoothHCIController 2.3.8f7
com.apple.driver.AppleUSBBluetoothHCIController 2.3.8f7
com.apple.iokit.IOBluetoothFamily 2.3.8f7
com.apple.driver.XsanFilter 402.1
com.apple.driver.AppleUSBMergeNub 4.1.5
com.apple.driver.AppleUSBComposite 3.9.0
com.apple.iokit.IOSCSIMultimediaCommandsDevice 2.6.5
com.apple.iokit.IOBDStorageFamily 1.6
com.apple.iokit.IODVDStorageFamily 1.6
com.apple.iokit.IOCDStorageFamily 1.6
com.apple.iokit.IOFireWireFamily 4.2.6
com.apple.iokit.IOAHCISerialATAPI 1.2.5
com.apple.iokit.IOSCSIArchitectureModelFamily 2.6.5
com.apple.iokit.IOUSBUserClient 4.1.5
com.apple.iokit.IONetworkingFamily 1.9
com.apple.iokit.IOAHCIFamily 2.0.4
com.apple.iokit.IOUSBFamily 4.1.7
com.apple.driver.AppleEFIRuntime 1.4.0
com.apple.iokit.IOHIDFamily 1.6.5
com.apple.iokit.IOSMBusFamily 1.1
com.apple.kext.AppleMatch 1.0.0d1
com.apple.security.TMSafetyNet 6
com.apple.driver.DiskImages 289
com.apple.iokit.IOStorageFamily 1.6.2
com.apple.driver.AppleACPIPlatform 1.3.5
com.apple.iokit.IOPCIFamily 2.6
com.apple.iokit.IOACPIFamily 1.3.0
Model: MacPro4,1, BootROM MP41.0081.B07, 4 processors, Quad-Core Intel Xeon, 2.66 GHz, 8 GB, SMC 1.39f5
Graphics: NVIDIA GeForce GT 120, NVIDIA GeForce GT 120, PCIe, 512 MB
Memory Module: global_name
Bluetooth: Version 2.3.8f7, 2 service, 19 devices, 1 incoming serial ports
Network Service: Ethernet, Ethernet, en0
PCI Card: NVIDIA GeForce GT 120, Display, Slot-1
Serial ATA Device: HL-DT-ST DVD-RW GH41N
Serial ATA Device: WDC WD6400AAKS-41H2B0, 596.17 GB
Serial ATA Device: WDC WD1001FALS-00J7B0, 931.51 GB
Serial ATA Device: ST3160023AS, 149.05 GB
USB Device: Hub, 0x05ac (Apple Inc.), 0x9126, 0xfd300000
USB Device: Display Audio, 0x05ac (Apple Inc.), 0x1105, 0xfd340000
USB Device: Display iSight, 0x05ac (Apple Inc.), 0x8508, 0xfd350000
USB Device: Apple LED Cinema Display, 0x05ac (Apple Inc.), 0x9226, 0xfd360000
USB Device: Keyboard Hub, 0x05ac (Apple Inc.), 0x1006, 0xfd100000
USB Device: Apple Keyboard, 0x05ac (Apple Inc.), 0x0220, 0xfd120000
USB Device: BRCM2046 Hub, 0x0a5c (Broadcom Corp.), 0x4500, 0x5a100000
USB Device: Bluetooth USB Host Controller, 0x05ac (Apple Inc.), 0x8215, 0x5a110000
USB Device: Optical USB Mouse, 0x046d (Logitech Inc.), 0xc016, 0x1a200000
FireWire Device: built-in_hub, Up to 800 Mb/sec

I can boot up in Safe Mode w/o a panic and I can also boot it up in Target Disk mode w/o crashing. the 29 instances of KPs is in the last two days.

Things I have tried:
1. running Disk Utility to repair permissions/disks
2. running fsck at the console level
3. running Cocktail on the drive from Target Disk mode
4. creating a new User Account with brand-new permissions
all of these have failed and it is looking like I'll need to re-install the OS. I'd rather not, as I'm not sure if I can find all of the disks/serial numbers for all of the software that has been installed prior to my arrival. tried to create a disk image in Target Disk mode but the process failed halfway through the night. I'm now on my third day of unproductive troubleshooting and the boss is getting itchy... any light on this would be fantastic.