Cannot open Powerpoint presentation in internet explorer

The in-place activation functionality seems to be broken
for displaying powerpoint .ppt files in Internet
Explorer. The in-place activation works fine for other
office files like Microsoft Word.

I have taken several steps to correct this problem but to
no avail. The MS knowledge base (article 193823) keeps
trying to insist to me that if I set the "Browse in same
window" option for the PPT file type that this will
magically fix my problem -- but it does not.

Any help would be greatly appreciated.