What edition of windows are you using?

I know it's a long shot, but I discovered that on my PC (Vista 64bit), the windows sidebar infrequently starts a second process in Task Manager and sits there using 40-50% of my CPU. possibly the same for 32bit....

I have located that when this occurs it (aside from clearly running and opening programs slower) also limits my download speed, as when I stop the procedure or close the sidebar, my downloads and all starts cranking once more.

So if it occurs again, check to see if you have a sidebar process running in task manager and observe if it’s using up your CPU.