Flash Drive Not Recognized "Hot"
Are there drive letter conflicts? Sometimes if a network drive has the same drive letter as the flash drive wants it causes this behavior. You can try using Administrative tools \disk management to assign the flash drive a different letter, that is not used by any drives on the network computer, if it can see the flash drive. I guess you could do this when you are off the network, just take note of all the drive letters that are in use when you are logged in the network, and pick a different one for the flash drive.
One other thought - Sometimes, once I have used "safely remove" a USB drive, it will not redetect the drive if plugged in the same USB port. You Might have to log off and back on to make it re-recognize it.