This happens to me as well. I'm running Edgy on a thinkpad laptop with a Radeon 9600-based card. Using the 'radeon' driver, external VGA works fine, but DVI doesn't work. When using fglrx, everything works fine.
Another thing that may be related:
cat /proc/acpi/ibm/video
shows "dvi: disabled" when using radeon, and "dvi: enabled" when using fglrx. This cannot be changed (in either case) by doing:
echo dvi_enable/disable > /proc/acpi/ibm/video
This happens to me as well. I'm running Edgy on a thinkpad laptop with a Radeon 9600-based card. Using the 'radeon' driver, external VGA works fine, but DVI doesn't work. When using fglrx, everything works fine.
Another thing that may be related: ibm/video ibm/video
cat /proc/acpi/
shows "dvi: disabled" when using radeon, and "dvi: enabled" when using fglrx. This cannot be changed (in either case) by doing:
echo dvi_enable/disable > /proc/acpi/