[Dual monitor] One monitor very dim after 13.04 upgrade

Hi all,

After upgrading from 12.10 to 13.04 on a system with two monitors, the second one became very dim. In fact, it's so dim that I thought it was blank. Both monitors are fine when booting up and they both show the "Ubuntu" name with 5 circles underneath...but somewhere during this point, the second screen blanks. By the time the login screen is shown, the second monitor is already very dim.

Thinking that this might be caused by incompatible configuration files, I created a new account and logged in with that -- no difference.

Thinking that maybe it's a hardware problem with the monitor, I swapped the DVI cables and the same monitor remained dim. I then plugged the monitor into another system and the monitor's fine.

This is the output from lspci:

$ lspci -v | grep -i vga
01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Cedar [Radeon HD 5000/6000/7350 Series] (prog-if 00 [VGA controller])

I'm not sure what else to try... Does anyone have any suggestions? Thank you!

Ray

Edit: Seems the second screen is fine sometimes (i.e., not always) right after the screen saver activates. I enter my password to unlock the screen saver and things are ok for a few seconds and then the second monitor suddenly dims.