Programs using extra CPU/100% CPU usage

[boredsomeone]

Hello, a friend of mine recently went back to using their laptop after their main computer died (Doesn't receive power, getting it fixed soonish possibly). Their laptop uses Vista, and they used to mainly use the laptop around 1 year ago. Since then, their parents sometimes use it to watch videos/movies, but that's about it.

The issue they are encountering is, after about 15 minutes of being turned on, the CPU usage shoots up to 90-100%, even while idle. This makes the computer, and anything she is running, start to stutter/freeze. This goes on indefinitely (tested over night, so at least 10+ hours). The laptop has 3 gigs of ram, and has played much more graphically intense/system heavy things before with minor to no stuttering/lag. We have both tried looking up possible fixes (listed below) but so far, nothing has helped.

Running multiple virus scans
Cleaning the registry (CCleaner)
Scanning for virus' while in safe mode
Installing updates (a good years worth)
Installing Service Pack 2


I've seen plenty of people asking about SVhost causing the issue, but SVhost runs at low/normal CPU usage during all of this. The main programs that shoot up at Skype, and a game we are playing (tried with multiple games, and we've tried with just one or the other). While idle, the CPU usage states that it's around 75-100%, but nothing on the process list shows that it's consuming all the of the CPU.

Just to compare to make sure it was the game/skype, I compared her usage to mine. During the first 5 minutes or so, the game was about 3-10%, only going up to 10% when we were actively playing. Then when the stuttering started, the game slowly worked its way up from 10, and evened out around 40-50% while idle on the game. Skype would shoot up to around 30-40% as well, with the rest of the programs running normally and taking up a grand total of around 10%

Any help possible would be very much appreciated, but if you want to suggest to do a System Restore, it's not currently possible (Their parents don't want to lose whatever they have on the laptop, apparently).

Thank you for your time.

 

[boredsomeone]

A bit more information.

We've tested it some more, and it would seem that the game we run (Any game we run) will run fine, the computer will run normally as stated for the first few minutes, but after a short time, the CPU will cap out as stated.

This means that any active program running seems to eventually cause an issue. I'm not sure if this will help more or not, but it's the most information we could gather so far.

We also know that it's not the computers hard drive not having enough space, they have a few 100 Gigs of space left.

Other things we've done now include Defragmenting and watching task manager to see if there's any suspicious looking processes. As for a system restore, they don't have the Vista (or any OS) installation disc on hand. Their parents most likely got rid of it at some point in time.

At the end of our rope though, not sure what else to try. Any tests we can run to find the source of the issue, or any help at all really would be appreciated. Thanks.