User profiles not accessable

I am only able to use my account which is the original one. I have 3
other accounts set up that quit working all of a sudden. When trying to
switch to them there is just a curser and blue screen and nothing else. I
tried deleting all the accounts manually as well (c:\users) and then tried
adding accounts again. The same thing just a blue screen. Did a system
restore as far back as I could no luck! Please help!

Thanks,

Brian