My work PC in the last couple of weeks has started exhibiting some odd behaviour involving images not being shown in desktop applications. Essentially, many images display just white space rather than the image itself. This has affected company logos on login screens, graphs/charts in various apps, and other logos scattered amongst third party software. Sometimes closing several apps makes the images appear again once an app is loaded, but other times a reboot is needed.
I suspect either a memory issue (although Task Manager never reports over 1.5-2GB in use), or the graphics card (a previous one died with a bang in this same PC), but I don't know how to ascertain for sure. The graphics card in question is a GeForce 8500GT and I've got two screens hooked up to it, while the PC is just an HP xw4600 Workstation running WinXP 32-bit with 4GB RAM.
Can anybody tell me exactly what's happening here, please? If something's about to fail, I'd like to get ahead of it.