If last year you had a new HD and more RAM, my guess is that the computer is a little bit older than one year.
Time to replace the motherboard battery.
About 2 weeks ago, instead of loading when I turned on my Windows XP Home computer, a message showed that my internal clock needed adjusting and to click on F4 to bring up Settings. I did this and re-set my clock which was showing Dec. 31, 2002. (My computer really isn't that old as little over a year ago I had a new HD installed along with more RAM; etc., and it runs beautifully.) However, when I exited Settings by going to "Save and Exit," the "Windows is Shutting Down" screen appeared. I let it shut down and then pressed the button to turn it back on again and this time it loaded normally.
Everything was fine. I finished working on my computer and turned it off as usual. The next day I received the same message and had to re-set the clock again. This has been reoccurring every day. I recently installed Microsoft's latest security patches (there were 11 of them) but can't recall if that was before or after the clock issue. Has anyone else had this problem? Is it indicative of something more serious? I don't like keeping my computer on all the time.