I recently encountered and fixed a perplexing problem with Outlook 2002 - namely, that any attempt to read a message resulted in a "Can't open this item" error.

What made it more confusing was the fact that I could open any type of item other than a mail message; tasks, contacts etc all worked just fine.

I repaired Office.
I removed and reinstalled Office.
I ran SFC on my W2K installation.
I reinstalled my security policy (I run under the securews policy).

No Dice.

And then, in a moment of inspiration, I reinstalled IE6.

*joy*

Obviously the HTML rendering components that are shared across Windows applications had become unstuck. I suspect re-running regsvr32.exe on the appropriate DLL would have done the trick, too.

I'm posting this in the hope of saving someone the day's worth of hair-tearing that I went through :-)