I got this through Donna (one of my favorite security blogs).
A recent patch, MS06-015, could cause some problems, such as:
• Unable to access special folders like "My Documents" or "My Pictures".
• Microsoft Office applications may stop responding when you attempt to save or open Office files in the "My Documents" folder.
• Office files in the "My Documents" folder are not able to open in Microsoft Office.
• Opening a file through an application's File / Open menu causes the program to stop responding .
• Typing an address into Internet Explorer’s address bar has no effect.
• Right-clicking on a file and selecting Send To has no effect.
• Clicking on the plus (+) sign beside a folder in Windows Explorer has no effect.
• Some third-party applications stop responding when opening or saving data in the “My Documents” folder.
And then there’s this little mention:
Well, it’s nice to be made famous this way, but the resolution is here, in KB918165.