PPT's flash to white in IE browser if temporary internet file already exists - cache/loading issue?

I've spent hours trying to troubleshoot this, and have reduced the
symptoms to this:
- Upon first linking to a PPT in IE browser, the temporary file gets
downloaded and the PPT slides show just fine.
- Upon 2nd & subsequent links to the ppt in a *new IE browser, slide 1
of the ppt briefly appears and then flashes to a white page, resets
the IE menu bar, and no ppt slides appear; unusable.
- If I delete the temporary ppt OR even open a 2nd/3rd IE browser, the
PPT displays just fine.

So if the PPT is in memory from the first download OR is in memory
from the 2nd/3rd attempt to load the temporary file...then the PPT
renders fine.

Only 2 of my 20 coworkers are experiencing this same issue.
There must be an IE, PowerPoint, or registry setting related to "fully
loading/refreshing cache" if file is not already in memory.

Any help would be wonderful.
Thank you!
Eric