This one cracked me up:
For what it’s worth, this error is produced by clicking any button on the Live Writer gadget for the Vista sidebar. (It’s a third-party utility, not one issued by Microsoft.) I suspect the problem is related to the mismatch between running a 64-bit Sidebar.exe with 32-bit gadget code, and other people have reported it as well.
But still … hilarious.
Update: I just got a note from Scott Lovegrove, the author of the gadget in question. He fixed the bug, got it approved by Live Downloads, and has the fixed version ready for download now. Thanks, Scott!
Ed Bott 
Classic!