Continual pauses every 10s or so

Hi all,
I'm having a weird problem with my computer, for about 3 weeks now, which is really quite irritating. It pauses for about 1-3 second in every 20-30 seconds or so, which might not sound like much but it gets really irritating really quickly, particularly when I'm moving the mouse or trying to type something.
It happens when I'm using Firefox, or gaming, or just browsing PDF's etc. I'm done the following (all with current defs updates):

CCleaner - to clean registry entries and temp files
MSE - full scan & clean
Spybot - full scan & immunisation
Tried ending processes that looked like they were hogging memory or that were unfamiliar to me (I keep myself well aquainted with them).
Restarting after doing all of this.

As a side note I keep getting logged out from an online game I frequently play and sometimes webpages take a long time to load (which is unusual), so there appear to possibly be some internet or router connectivity issues or such.

I'm not really sure what else to do and it's just driving me crazy. Any other steps I can take to diagnose?

 

Ok thanks, will do.

 

Have you shut down completely then restarted?