SECOND MONITOR "NO SIGNAL"

This is really bugging me:
I have 2 19" Viewsonic monitor on an ATI RADEON HD 4850. When i boot up my pc both monitors are running fine until VISTA 64 sign in, the second monitor goes no signal.
I have a Gateway FX6800 ie
VISTA home premium 64 bit
3G RAM
750 HD

Steps i did:
1. Calling Gateway --- uh, spent 1 hour with the guy from india, nothing resolved, he wants me to call a 1800 number and pay for the service. I am under warranty btw.
2. Updated ATI software from 8.6 to 9.4 to 9.5 (installaton out of disk space error) SO i went back to 8.6
3. Uninstalled display driver and suddenly the second monitor goes on. Cool. But now i dont have a catalyst software and the screen looks terrible on both monitors.
4. Restarted PC, both monitors running and online. Vista looked for the display drivers and automatically installed it. Prompted me to restart. After restart, everything goes back to before, second monitor is offline again.
5. I tried stopping vista from automatically installing software through system and device configuration and prompt me to install the software.

Please guys if you have an answer to this please email me at Glynn@optonline.net for anything that might be done.
Thank you.

I have 650 GB free out of 750 GB. There's no way i am out of disk space