The power supply.
It may be dying. I'd replace it. Now. A glitch can cause corrupted and loss of data.
My 2.5 year old PC
AMD Athlon XP 1800+
MSI KT3 Ultra2 (KT333) Motherboard
896(512+256+128) MB DDR RAM
40 GB Seagate HDD
Asus GeForce 4 Ti4200 128 MB RAM
Samsung 753S 17" monitor
Kobian KOB85 cabinet with extra fans in front and back
running Win XP Home SP2 with Norton SystemWorks 2003 and MSI PCAlert4
I have been having trouble a couple of times in the past week.
Since I have a recent broadband connection the PC is on for at least 15-18 hrs/day.
I noticed that whenever I try to play a video clip on MediaPlayer the whole thing used to slow down to a crawl. Otherwise the machine was ok for other tasks only slows while playing video.
Then when i started PCALert I noticed that the window for 3.3V was in the red and showed voltages ranging from 2.91 to 2.96 V and there was the alert sound. here is a screenshot- http://server2.uploadit.org/files/cbh5150-pcalert.jpg
It has happened only twice this last week.
What could be trouble? Is it big trouble needing immediate intervention?