I am willing to bet that the root issue is with the host and one of these situations is occurring:  A) the host is throttling your processor resources and shutting your domain down after unusual activity occurs on your site.... B) total activity on the server (your site and other sites) exceed a certain level and the server limits resource available for processing.

I would be looking for a new host.

Prepare your powerpoint slides as usual.  Be sure to add a few links to related pages on your website (backlinks from powerpoint presentations will display in your google webmaster tools).  And, be sure to include lots of keyword relevant text.

The most important thing to do is edit the "properties" of the file.  This will allow to give the presentation a title that will be used similar to a title tag by the search engines.