xp resets my profiles when i restart

[Terry]

Hi there, this is an annoying problem (as they all are!).

Everytime i restart my PC, when i turn it on again all
the settings and programs that i installed or modified
during the last log on are reset so when i try to check
email i have to re-enter all the login info etc, and the
programs i install just dissapear!

I have no idea what i've done but can anyone suggest what
might be causing it?

Thanks
Terry