I solved the problem, but it was by doing something that was a bit odd.
I found a link where someone was having the same problem I was, where previously when I had attached external storage I would receive a generic volume message telling me to contact the vendor.
Here is the advice. It worked for me, non more messages, everything can be read - worth a try for others...
_Hi. I started getting the same error message when I tried connecting a PNY Flash Drive to my USB port. Here's what worked for me. This may be unique because I caused the problem myself.
Like many people who are trying to speed up Windows or slim down files or tweak this and adjust that, I use some (not so reliable) hints and tips I have read. I followed certain steps posted at an url called "How can I delete undeletable folders?", wherein a poster named "********" gave instructions for removing Netmeeting, MSN Gaming Zone, Xerox, Movie Maker, and Microsoft Frontpage from the Program Files folder. Seemed like a plan to me. But then, as I recall, Custer had one, too. Unfortunately, blindly following his advice and renaming SFCFILES.DLL to SFCFILES.OLD and then removing these folders in Safe Mode caused the "device installer error". I deduced this by restoring the system day by day backwards until the error messages went away. Renaming SFCFILES.OLD back to SFCFILES.DLL and rebooting XP made the folders come back and the error messages go away. My Nikon D70 is back and the PNY Flash drive loads just fine, thank you very much._