false restarts

Hi, Using Win XP Home, now SP3 on Presario SR1500NX from 2005. Back in November, I was googling a recipe & the link was redirected, I think. A popup said my antivirus was out of date and to click for a download/update. Didn't Believe it! Had trouble getting out of it, so Closed the tab & then browser (using Firefox). Couldn't open it, only got the icon/info on status bar, had to Ctrl Alt Del it. Later deleted Firefox(loved it). Sometime later, got "Missing Operating System" on startup. Worked around it until I found Bios Update & installed it. Meanwhile, was told it was hard drive problem, but found info on testing it & did the extended test for 12 hours, no errors. Same with memory using windiag.iso, no errors. Later, Works v8 crashed, couldn't open anything (10,000 short files). Downloaded McAfee from Comcast & RegCure & OpenOffice(which doesn't open my files, so need another free download to open each file, convert then open in OOO or a new Works V8.5 or 9). Ran them both multiple times, don't know where to find LOGS, if any because ran with immediate fixes & had no time to read the messages.

Now, without being online, running a solitaire with other simple DOS-games in background, they all popped up as if just starting, several times. Another time, the open but not used browser & everything else on status bar disappeared as if starting from a reboot. An XP SP3 problem????

Thinking I did have an intermittent hardware problem & to be safe, I bought a new, inexpensive PC. But am wondering if I should or should not return the new, unopened PC.

Any Ideas about these false restarts??? NEW PC???

Thanks in advance,
MarieDesi :confused

 

first try reformatting the hdd and reinstalling the os, sounds like you have some kind of malware on your system

 

Thanks Arvald & Major Attitude,
I saved your malware removal guide & downloaded Malwarebytes' Anti-Malware 1.34. I also ran msconfig & set to normal start. Then ran the Anti-Malware which found C:\Program Files\Perfect Optimizer (Rogue.PerfectOptimzier) and about 125 files in the folder. I then had it "fix" them and McAfee started running, so I went to bed.
I still haven't googled Perfect Optimizer. Maybe that will help! Am so against reformating C:-- so much to reload afterward! I have files in a McAfee backup on another drive F:, and am not sure if a reload of McAfee would be able to find them & restore them. So will just copy files over if room (~ 16GB available and 21GB used)
Thanks for your responses.