Windows failing?

> I began to get error messages with applications
> shutting down in mid-flight. [Unexpected error, I
> believe, and Windows Explorer or Word was terminated--
> sometimes with items "recovered".] It especially
> happened if I tried to open a graphics file from explorer.
> Now, every time I tried to turn on the computer, it
> loads slower and slower. I tried to do a "restore", but
> the 2 dates I chose could not be "restored to", and I was
> afraid to try it again.
> Can I reinstall Windows to correct whatever may be
> wrong? Or is there another answer to my problem. I'm
> fearful of logging off, in case I can't get started again.
> I tried sending report as instructed to do on the error
> message, but I can't find a report back to me to explain
> the problem.
> Help! someone please!!
>