Storage forum: USB Thumb drive won't work w/printer on. (Long Story)

Hi
I have a Dell Dimension 4550, Pentium 4 @ 2.53GHz.768 MB, 60Gb hard drive, 250MB Iomega 250 Zip drive, A Lexmark X3550 printer, Running Windows XP Home edition.
My son had 2 thumb drives for his home work and they work fine. I got a virus, and computer would keep re-booting, Computer guy came over and had to take computer and wiped the Hard drive. I got it back and re installed my progams, but it still would reboot at time, with his help I found 1 of my menory modules to be bad. Everthing seam to be working fine, then I get the MS antivirus 2009 poping up, won't let me update antivirus or run sone malware progams. He came back and couldn't fix it and suggest it was time to get a new computer, but I can't afford one now.
So I keep messing with and reading on how to get rid of it. Found Cnet web site and now I have fixed that problem.
Now my problem is my Sandisk Mirco Curzer won't work at times, I check it on other computer and it work fine, I bought another one PNY Attache to try, same problem.
I tried what was suggest on Spyware forum and was told to try here.
When I go to my computer and check disk management, it shows the Sandisk as 2 drives
(1) Sandisk Cruzer USB Device
Device type : DVD/CD-Rom drive
(2) Lexmark USB Mass Storge USB device
Device type : Disk Drive.

I got to thing about the early problems and I found when the printer was turn off the computer work fine. I remove the printer software and re-install it and down loaded the update for it.
Still have the problem of the thumb drives not working, but when I turn off the printer they work now. With the printer on everthing works, but the thumb drives.
I was thing about upgrading to a wireless Lexmark printer, but don't know if that will fix the problem. Any ideals on what to do to fix this?
Thanks
Rick