What could it be?

I have a pretty good computer... 2.5 GHz dual core, 4GB RAM, etc. yet I am experiencing problems recently. On startup I have about 8 things running, 8 programs, not huge programs but typical security programs and such. Half of the time when I reboot, I freeze with an hourglass cursor. If I cut that down to about 5, I seem to boot up fine. Also, when I am playing music or video sometimes, I freeze up. Sometimes I will have a period of 30 minutes where every 15 seconds I will get a small freeze for about 2 seconds.

I've used NOD32, Malwarebytes', Spybot, etc. to check for malware, viruses, etc. and I seem to be clean. What could this be? What can I do? What are some programs I can run to check just in case?

 

Sounds like a live scanner of some type that kills the music/video.

 

http://i30.tinypic.com/9qa0p1.png
http://i28.tinypic.com/1hugsn.png

 

Possibly the search indexer or another app triggered by Task Scheduler - defrag is sometimes a problem.

Checking the System logs may also shed some light on the problem.