Display settings on XP keep changing....why?

Well, I'm having an issue with Windows XP and according to my scans (checked by the malware folks yesterday) I do not currently have an infection.

Yesterday morning when I booted up, I noticed that my desktop display settings had changed. I normally use the Windows classic view/theme (gray toolbar/start button) but when I booted things had changed to the Windows XP theme (blue toolbar/green, rounded start button). I immediately went into virus scanning mode because last time this happened (about 2 weeks ago) it was the initial sign of an infection. As I mentioned earlier, ran the Malware forum scans and the mods said I'm clean. After I ran through the Malware forum's final steps (including flushing the restore points), on reboot, my settings went back to Classic view.

But, AGAIN, this morning when things booted up the Windows XP theme was back! I'm am very concerned and totally perplexed by this! If I do not have an infection, what could be causing this? I really don't care for the Windows XP theme, but that is really just cosmetic I guess - I'm more concerned that this could be a sign of a deeper issue.

Any advice is appreciated! Thanks!