Problems with a new processor

[Shoe]

My computer recently crashed... it turns out that I needed a new processor.

I ordered an OEM processor (not sure if that makes a difference). My old processor was a 2.8ghz, this one is 3.0ghz.

I had a friend install it for me who does a lot of computer stuff.

The computer works again, however the processor has times where it just freezes, such as sometimes when i try to open an application or just a web browser or something it will just freeze for 30 seconds or so. When looking in the task manager the processor is at 0%, so it's not thinking or anything, eventaully everything gets back to normal but these freezes and slowdowns are driving me crazy.

Does anyone know if there is anything I can do?

Also, ever since installing the new processor, my anti-virus will not automatically be enabled on startup (even though that option is checked). I need to manually start it every time i restart now, and it seems to disable itself at random if I am playing around with settings or installing something. Any ideas? Thank you in advance.