Ok, I have found the answer in the MS KB. It's for VB but as pywin32 is only a wrap around the API the same is applicable to the python code. Here is the link to the article in MS KB: http://support.microsoft.com/kb/259971
EDIT: since the link is dead, there is an archive of the KB here: https://www.betaarchive.com/wiki/index.php/Microsoft_KB_Archive/259971