CPU at 100% every 6 min

This has been an issue since late last year, so far I haven't found a way to control it.

 

The PC is running XP with SP3, 2GB ram. I am a regular user of Photoshop which freezes for 8-10 seconds when each spike occurs.

 

I have uninstalled Internet security using the current tool and reinstalled. I am runing with Idle Time optimiser off and photoshop listed as a program to enable quiet mode, I normally run it full screen.

 

Enabling silent mode has no effect. The activity doesn't start as soon as the PC is started, I will see if I can find out when or what triggers it tonight.

 

Suggestions please

 

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