Any ideas what's wrong with this Lenovo laptop?

[Heerlo]

So someone my aunt's husband knows has a laptop, which he hasn't even had for a year. Although I think it may have been used before he had it, it's still apparently fairly new. It has Windows 7, and a dual core Pentium CPU.

But it's EXTREMELY slow. In fact, it's trying to open a web browser as I type this. There doesn't seem to be any reason it should be this slow. It has an almost three hundred GB hard drive, and it's not using nearly all of it. It's not bogged-down hardly at all. It barely had anything on the desktop before we started working on it. I used Spy Bot Search&Destroy to scan it, but it just almost instantly finishes the scan and says it found nothing. I also thought the CPU could have been over-heating, but I got a program to check it and it's idling about 45 to 50 degrees C, which I don't think would be causing it to be so slow.

I know this isn't a generally computer-related forum, but I would appreciate any advice anyone could offer. Thanks.

Edit: Also wanted to mention, this laptop very commonly has Windows Explorer crashes, in case anyone knows what causes that.

Edit: My brother has reinstalled Windows 7 on it and it appears to be better now.

 

[warpus]

Open task manager. Check CPU activity. Is it close to 100%? If so, check what process is eating up all your CPU cycles.

 

[Heerlo]

I don't know what was wrong with it, but reinstalling Windows seemed to make it alot faster. So I thinks it's okay now.