PC is a 7 yo 1.6 Ghz DELL with 1 Gb Ram ... running XP Home SP2. 20Gb hd for C: and E: .... 120GB 2nd hd for D:, F:, G:, and H:.
Scanned for virus last week with Avg and for spyware with SpyBot and Ad-Aware. System clean. Use Ccleaner almost every night (but didn't last night ... cause of problem? Don't think so because have not run Ccleaner before and never had the problem).
Defragged C: about 3 weeks about - have 2.5Gb free on system drive (C:).
Would an old CPU battery do this? ... haven't lost time/date ever.