Blank screen when switching video output & resolution w/ATI 4870

Info:
OS: Vista x64
Card: ATI HD4870
Monitor: Samsung 22in LCD w/resolution at 1680x1050
HDTV: Panasonic 46" pz850u w/resolution at 1920x1080
Drivers: Catalyst 9.6

I seem to have a problem when I use the Catalyst Control Center to switch the video card output from my monitor to my HDTV...the screen goes blank and I have to restart my computer. Unplugging the HDMI cable doesnt help either.

To be even more specific, it really happens when I go from my HDTV with a higher resolution to my monitor(blank screen on both). However, when I go from my monitor to my HDTV it works ok, BUT the resolution on my HDTV is at a lower 1680x1050 and when I try to change it to 1920x1080 the screen goes black. When I reboot my computer, the resolution is 1920x1080 and the output is on my HDTV...but then I can't switch back to the monitor(black screen) so I'll reboot then it's back to 1680x1050 on my monitor.

Steps that cause the problems:
1. Monitor is up and running normally at 1680x1050
2. Use CCC to switch output to HDTV...it works, but TV resolution is also at 1680x1050
3. Use CCC to change TV resolution to 1920x1080(BLANK SCREEN on both)
4. Reboot PC and TV comes in at 1920x1080(good)
5. Use CCC to switch output to monitor(BLANK SCREEN on both)
6. Reboot PC and monitor comes back in at 1680x1050(good)

Any ideas? I've cross posted on other message boards with no help yet.

Edit: Looks like I can switch back to the monitor from the HDTV. It seems the problem is:
1. When output is on monitor and I use CCC to switch to HDTV, it doesn't hold the 1920x1080 resolution and puts the HDTV at 1680x1050.
2. When output is on HDTV, I can't change the resolution without the screen going black.

I'm using a ~30ft HDMI cable...dunno if that make a difference.