Can't find files

[David]

About two weeks after I bought my HP Pavilion PC I began
experiencing problems. My MSpaint program just
disappeared and I can't find it. I don't know how to get
it back.
On top of that, every time I turn my PC off or restart
it, it says something like "Windows experienced an error:
Send error report/Don't send error report" What could be
wrong with my PC? Any advice would be greatly appreciated.

Thanks, David