Question : Problem: USB flash drive problem, no drive letter, no access

I've got USB problems,  have researched all the USB drive related issues, no answers for me yet. My  problem is this:  I have had 3  computers suddenly "give up the ghost."  when it comes time to recognize and assign a drive letter to a USB flash drive, or a USB zip-750 removable disc, or a camera dock for casio camera.  All these devices normally work in winxp with no drivers, and no installation..

I've checked all the mapped network drives, other issues, no help.  THe flash drives (three of them, 2 sandisk 1 gig, 1 other,  the ZIP 750 is Iomega)  all work fine on other computers. I thought it might be some software utilities that I've used, but no, I've tested that theory to exhaustion, I get no problems on other computers.  

WHat happens is this: 1) plug in drive or insert zip disk.    2) computer "beeps", and the icon shows up in systray for "mass storage device", so I know the hardware and part of Windows(XP, SP2)  knows its there.    3)  no drive letter in explorer.    4)  go to Disk Management,  the drive shows up as a FAT or FAT32 drive,  I try to assign a drive letter,  I get a message that the "device is not enabled,  restart computer to enable device."
5) multiple restarts, no help.    6)sometimes, I can assign a drive letter, and access the drive through that letter by typing it into explorer, usually not.  After I unplug it, and plug back in,  then I cant use that letter anymore, and the device is not recognized.  The drive letter shows up in explorer, but no good,  it gives me various error messages when clicked.  after restart, I can use that drive letter again.

I do have a habit of making images of the boot drive every month or so.  In each case, when I restored an image from late november 05, or early december 05,  the USB problem went away.  I  restored images from Jan 06, Feb 06,  in each case, the problem came back immediately.  

This tells me that it's a windows issue, the hardware is all working fine, and works perfectly  (assigns drive letters, autoplay ok, removes drive letters when I unplug, etc.)  when I restore a hard drive image  (boot drive  only, all other drives/partitions are the same)  from  12-05 or so, and then goes crazy when I have a more recent version, with more windows updates, and some software changes.  All three computers have different motherboards, I do not use drivers from sandisk, iomega, etc, the windows drivers work fine when they work.

Any help out there??? I suspect it has something to do with the way that windows assigns drive letters, but have tried all the fixes on this board and several others.  I KNOW it's not a hardware problem,  I KNOW it's windows, possibly incombination with other software, but I'v installed/uninstalled several large packages  (roxio 6,  roxio 7,5) and some smaller utilities, backups, etc,  too numerous to mention, plus the "mix" of software is different on all three computers, so I'm pretty sure that its WINDOWS alone that's causing this problem.  THanks,  JOhn S.

Answer : Problem: USB flash drive problem, no drive letter, no access

This has become a common problem that is caused by Microsoft's security patches.  Here is a thread that covers this issue, some with a lot of detail.  Maybe one of these may help:
http://techrepublic.com.com/5208-11183-0.html?forumID=89&threadID=192306