Try setting the explorer to details view and try to make it stick for all folders (near impossible for vista).
I bet vista is crashing trying to make thumbnails of pcx textures or optimised bitmaps. Plausible, as some textures may crash vistas "thumbnailer" while others do not?
edit: I tested my theory (however on my system
aero is off and I have all SFC apps installed to C:\SFC\*), and what I observed was that when switching from "details" to "large icons" in the EAW models folder and scrolling down to the bottom - it maxed out one cpu for about 2 seconds - but did not crash. However, the timing and symptoms are very close to what you describe.
You could try scanning your models folders (or whole system?) with A-Squared Free Portable to check for malware:
http://www.emsisoft.com/en/software/stick/(can just be extracted to a folder, does not have to be on a usb stick, but its handy to have it on one.)
However if you scan the whole system with it, be aware that it is very suspicious of everything and will flag many items that probably are not of any serious concern. The trick is with these apps is that the average user does not know enough to filter out the false positives.