Thank you for answering the questions so thoroughly. That will definitely help.
All we have to do is figure out what happened three days ago and reverse it.
I would guess that this didn't begin happening in the middle of a session with
PowerPoint, but if it did, that is key information, so please let us know.
Can you remember if and what you installed several days ago? Have you tried
restoring the system to 3 days ago using System Restore? Go to Start > Help and
Support, you should look for an item under Pick a Task that says "Undo changes
to your computer with System Restore. At this point you don't want to actually
do a Restore, but it will be helpful if you look to see what restore points have
been taken since just before your problem occurred.
So, click on "Undo changes to your computer with System Restore". On the next
screen, leave Restore my computer set and click on Next. You'll see a calendar.
Any date that is in bold means there was a checkpoint taken on that date. Click
on yesterday, and then the day before that, and you'll see more details about
the reason for the checkpoint. Do you see any that were taken when something
was installed or removed from your system? If so, what was installed?