Safemode and graph. card

Hey!
I have 2 things i wonder about:

- Sometimes (haven't checked often since reinstall) i experience that the computer doesn't respond in safemode. Like, neither mouse of keyboard works.
Another problem has been that i can't log on with password in standard (think it's named "quick user change" or something.

- My screen, flimmers in some conditions. I haven't been all around, but i experience flimmers when entering screen for selecting safemode and in safemode. I do also get flimmers when i launch battlefield 2 (only in menus and loading map).

Can you help me solve these?
Greetz