Updates to OS, antivirus and more can cause odd things like this. As I see a change in how folk write apps they tend to just task the CPU to get it done rather than code carefully anymore.
Why not stop Sidebar? I did long ago.
Bob
Every so often my cooling fan kicks on as my CPU usage jumps to 80-90% for no reason that I can see. It's a 3-4 year-old Dell Studio desktop with an Intel Core 2 Quad, running Vista, and it just started doing this like a month or so ago.
When it happens, it seems to happen in bunches. i.e. be okay for a day or so, then bang: fan on like every few minutes for 20-30 minutes.
I can see the CPU usage on a widget, and it jumps up into the redzone when this happens, and then falls back to normal when it stops. Memory usage also seems to rise to ~50-60%. It even happens when I'm running nothing but MSWord
I've checked Task Manager, and I don't see anything really notable, most activity in a process called Windows Sidebar. The fan grill is clean and gets plenty of air. Does anyone know what's going on? Should I be worried?
Any help appreciated.

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