Just recently my monitors have been acting up. I have two Acer AL2423 w Monitors configured in dualview. Recently both have been giving me trouble. The "no signal" dialogue box appears in the center of the screen though both seem to be working. Also one will flicker off and on while the other will flash to a screen of rainbow colored horizontal bars. I am currently running them with Nvidia GeForce 7300 GPU. Any ideas?

The 7300 series most definately supports a dualview setup. My only thought is that you may not have the required ForceWear driver for the 7300 series. you can pour over the specs here: NVIDIA® GeForce® 7 Ser
and see if you find anything else of interest.
The current release for ForceWear is 158.24 for Vista (64-bit), which you can find here:
NVIDIA Drivers
Hope that helps