Hello and welcome to Bleepingcomputer.
I see where you stated your computer was performing the way it was supposed to and then for no apparent reason, the computer tends to take a sudden time out and then resumes acting normal again.
There may be a program that is occasionally using a lot of resources that is doing some routine business.
This could include an anti-virus program, or a program that checks for updates by checking in with a web server.
If your computer is not suffering from any heat related issues, I would try downloading Auto Runs at this link and install it, start it and see what programs or processes are designed to run.
The other program is Process Explorer, this program will show you what processes are running at any given moment, anything that shows up with a dark red high-light is a program that is using a lot of processing power at any given moment.
Auto runs http://technet.microsoft.com/en-us/sysinte...s/bb963902.aspx
Process Explorer http://technet.microsoft.com/en-us/sysinte...s/bb896653.aspx
Good luck and hope this helps you diagnose what is happening during those momentary freeze ups.
Edited by MrBruce1959, 18 August 2010 - 12:50 PM.