ASP.NET: Failed to start monitoring file changes.

A few days ago, a customer called because an ASP.NET application we wrote failed with the errormessage:
"Access denied to 'x:\xxxxxxx\xxxx\xxx\xxxx.aspx'. Failed to start monitoring file changes."
That application had been running for months without errors.

We did a lot of searches, most of them pointing to:
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q317955
and
http://support.microsoft.com/default.aspx?kbid=316721

But the problem persisted.
Totally clueless I decided to do a last search... and I found this:
http://support.microsoft.com/default.aspx?scid=kb;en-us;824308
Nice bug ;-)