I am at my wits end and a begging for any advice or assistance to get me over this hurdle.

I have a new pc:

Core2 Quad Q9550 @ 2.83GHz
Gigabyte GA-EP45T-DS3R mobo
4GB DDR3 1600 RAM
H.I.S. H487F512P 4870 Graphics Card w/512 Ram
Vista Home Premium 64-bit
Western Digital 10,000rpm 160GB main hard drive
Seagate 750GB secondary hard drive
Liquid cpu cooling
Dell 2408wfp monitor connected via HDMI (converted from DVI)

The pc was put together by and purchased from Cyberpower. The graphics drivers were the Catalyst 8.10. My first attempt to launch windows media center led to a black screen. Nothing would "wake" the pc short of a hard reboot. Since that time I have confirmed that every single attempt to launch Windows Media Center will create the same thing. In addition, a number of other actions will cause the same unwakeable black screen some or most of the time including:

* Switching Users
* Logging Off (doesn't actually log off - just gets stuck)
* Logging On (after entering password). This is sometimes accompanied by a single fast repeating note from the speakers while it is locked up. This typically takes place after a hard reboot.
* Launching Picture Show
* Screen saver (if I leave the pc for sometime I return to an unwakeable black screen)
* Hibernate
* Installing a program (happened while installing 64-bit iTunes)
* Launching a program (happened while launching iTunes)
* And a a number of other actions I am not thinking of at the moment.

I have tried clean installs of 8.12, 8.11 (could not even boot up past the mobo splash screen after installing 8.11), 8.10 again. I have also tried a complete wipe (delete partition, format drive and reinstall Vista) on three separate occasions and a step by step from there. The problems start occuring immediately after the installation of the Catalyst drivers - even before I change the resolution to match the monitor. Before Catalyst I could launch media center - right after - black screen.

Thank you in advance for any assistance you may provide.

there is 8.12 now available can you try this???

have you tried updating your bios???

GIGABYTE - Support&Download - Motherboard - BIOS - GA-EP45T-DS3R (rev. 1.0)

I had attempted clean installs of 8.12 and then 8.11. Same problems with 8.12. Problem was even worse with 8.11 in that I was unable to boot past the splash screen. I have rebuilt Vista from scratch (deleted partition, formatted the drive and re-installed Vista Home Premium 64-bit) on three separate occasions. I have removed drivers and reinstalled 8.10 & 8.12 on three occasions each and 8.11 on just the one occasion. I am flat out stumped.

so have to update your bios???

as sygnus suggested do you have a warranty???

also have you tried this??

http://support.ati.com/ics/support/K...folderID=11020

the last one saying HD4800 hotfix...

have not updated bios. I am currently under warranty. They suggested rebuilding Vista - which I did. I have left several messages for their tech support since. They are not especially responsive for a company supposedly offering 24/7 support. I have removed and reinstalled drivers at least six different times to this point.

have you tried the hotfix??
if that dosent work RMA it.....

not yet. Trying that next. I will report back. Thank you.

hello sygnus...
8.12 Vista 4850 hotfix.... some clarification - Rage3D Discussion Area

this is where the discussion on this problem...
although you see 4850 it does apply to 48xx including 4870

it seems to happen where people have more than 4gb of ram...