BleepingComputer.com: OS changed magically !

Hello Again.
Here it is.
Yesterday my acer e380 desktop was running like a charm. My girlfriends son was on it last night and when I woke up this morning the OS had changed from xp home to xp pro. I asked him if he changed anything and he said no but im not so sure. I do have a copy of xp pro burnt to my harddrive.
Ever since the changes I cant run the following
-malwarebytes
-superantispyware
- system restore
lots of error messages loading programs.

All I want to do is restore back to xp home but cant do so through the system restore option.

Oh, Is there some software available to try that will monitor whats being done on the computer. Not necessarily for the internet as I know all he does is play online games. I just want to see if hes modifying or changing anything in the system.

I spent alot of time with people on this forum getting my system to what I thought was at peak performance,now it seems all for nothing. i really need to see what hes playing around with.
thanks

Well...no installed O/S ever changes to a different one...without human intervention.

That premise should tell you what you need to do.

Louis

thanks.
I figured as much but wanted to be sure. What about some monitoring software?
Any ideas

Personally, I have no experience with monitoring software but others here do...so wait for inputs from them.

Louis