in taskmanager, System is periodically taking 26% of CPU power

[tak3shiro]

so, to the best of my knowledge, it's not a virus or spyware. =(
it says,
System SYSTEM 0
then will jump to
System SYSTEM 26

 

[mechBgon]

Try the Microsoft AntiSpyware beta: link.

Also, is McAfee fully updated? It should have the 4.4.00 engine (may be represented as 4400) and the 4453 DATs (virus defs). You may want to try a full McAfee scan in Safe Mode.

Bigger picture: do you have any particular reasons to suspect spyware? Is your system doing something in the background (P2P-type stuff comes to mind)? How often does that happen, and how long does it last?

 

[deadseasquirrel]

Go grab Sysinternals Process Explorer. Have it running and you can then see what programs are using that periodic spike. If it's something like explorer.exe or svchost, you'll be able to see what DLLs and services inside those are causing the usage.

Might help you find something useful.