Flat white screen

Hello,
I have desktop PC with GA-MA69GM-S2H motherboard, 4gigs ram, integrated relatek sound and ATI radeon x1250

problem:
After restart win is loading properly until logon screen..... there is no logon screen!!! only flat white, nothing more. But when I type my password it's continues loading.

I've been trying to instal Ati latest drivers but i have errors while installing.

Help.

P.S.
I dont have sound too.
P.P.S
On my laptop Amilo Pro v3545 averything working fine.

I have a GA-MA69?-sh3 gigabyte motherboard an a ati radeon x1250. When I booted with 2 gigs of ram, everything worked fine. I latter added 2 more gigs of ram. This produced a white screen. I did not try to log in. I did run a memory check on the ram. Checked out OK.
When I removed the added 2 gigs, every thing worked fine again. Tryed new ati driver-did not help.

weird, im having the same issue with the white scrren but even though I take out and/or switch around ram sticks I'm still having same issue.