Success At Last...
3rd party drivers can be installed when Windows doesn't provide them, and it's sometimes necessary as found with the new Belkin USB 2.0 PCI card I'd recently installed. Got that working after reinstalling the driver from CD, but these old Buslink USB 1 drives won't work no matter what. Driver installs, but XP fails to recognize it, and this only happened after I stupidly removed the driver to re-install after it failed to fire up. Before, the driver installed automatically without need of the manufacturer supplied driver. This should have been the first red flag that all was not well. Had I daisy chained these drives, or not tried to switch between the two (hot swappable) drives to search for a file, one of the two drives would still be working.
None of the external Buslink firewire, firewire/USB combo, (or SATA/firewire/USB combo) drives are having a problem, and so far HP printer is holding tight, as is HP Scanjet, APC Back-UPS, external Sony combo burner, keyboard, mouse, and these old USB 1 drives were working fine up until lately. I begin to wonder if it isn't as you say, conflict between USB 1 & 2, so may give Belkin a call on Monday to ask. What makes this hard is that the old USB drives aren't nearly as valuable to me right now as is my Wacom tablet, so between the two, the Belkin USB card is going to win precedence.
This is a Dell Dimension 8200, around 5? years old... and while slightly outdated, is still enough of what is needed to make most things work relatively well. Until recently everything did, and the biggest change made to this system is that Belkin 2.0 card.
UPDATE: After speaking with Buslink support and taking advise to purchase 3.5" USB 2.0 enclosures to update these outdated USB 1.1 drives, all is well again with my hard drives. No more driver conflicts, and these new enclosures are beautiful by comparison to their yellow mustard faced ones, and only cost $15 each at XPCGear.com.
I might add that original suspicion about Windows updates was most likely what caused system instability. After reading this most recent patch information, I'm convinced of it:
"Update for Windows XP (KB929338)
Typical download size: 725 KB , less than 1 minute
This is a reliability update. Install this update to improve the stability of computers running Windows XP. This update prevents some Stop 0x1a or Stop 0x0a errors. After you install this item, you will have to restart your computer."
This is precisely the problem I was starting to have and nearly cost a fresh install. So far I've managed to salvage this OS and nothing so far has failed to work since upgrading to USB 2.0 and chucking USB 1.1 devices. I'm thinking Windows XP Home does not handle them well anymore with all the changes that have been made to it in the name of improved security.