Unable to run Excel, similar problem with Windows Explorer

Inspiron 8500

for several months I've had a problem with Windows Explorer sometimes crashing when browsing files/folders. I get the window in the middle of the screen that says "Windows Explorer has encountered a problem and needs to close. If you were in the middle etc etc......"

Sometimes it's trying to open specific folders that cause it to crash, though if I drag the folder say onto the desktop, I can access it.

However it's one of those problems I can live with while there's more important things to do.

Last week during a power cut, the computer shut down and I had the blue screen when I restarted it. However, after restarting, all seemed ok.

Except now I can't use Excel, but all other programs seem fine. I get the same window when I try to run it, it doesn't get beyond the splash screen.

I reinstalled Office. No difference.

I ran a Windows repair with the original CD. No difference.

I reinstalled SP2 from CD, although this too crashed during the final stages of installation, though it seems to have installed OK.

Can anyone advise what might be the problem?