Issues with freezing

I don't get it.
SP3 will make my computer stop freezing up? I somehow doubt it. I once installed it, it didn't allow me to connect to the internet, so I deleted it.
I also doubt a newer Adobe Reader will help.
As far as browsers, I currently use Firefox.
If there's anything else you think is worth trying, please let me know. Otherwise I guess I'll have to format my harddrive, and start over from scratch.
Thanks again for all your help.

Ok looking at the spec the PC is a little old? 2-3 years?

Now in my experience freezing like this is one of 2 problems (but can also be malware and stuff like dragon is saying)

1) Bad sectors on the hard disk

2) CPU over heating

Can you tell me does anything else cause the freezing? Do you play any sort of games or anything that causes long term high cpu usage? Do you have any sort of temperature measuring software?

How to check and "repair" bad sectors:

For Windows

1) Double-click on My Computer to open the My Computer window.

2) Select the disk that you want to diagnose and repair.

3) Choose Properties from the File menu. You should see the Properties window for the drive that you selected.

4) Choose the Tools tab.

5) Click the Check Now button under Error Checking Status.

6) Depending on your version of Windows, choose either "Thorough" or "Scan for and Attempt Recovery of Bad Sectors."

7) Click on Start.

Moved to a new topic, so others can help.