I have an Acer Revo 70 nettop which I use as my main computer running Xubuntu 12.04. It outputs to my monitor via HDMI at 1920x1080 resolution. I bought a "Y splitter" that splits this output into two, the other going to my TV so that I can watch movies etc on my TV as well.

Problem is, when I turn on the TV with this y splitter in place, it works for that session but subsequently the resolution on both devices reverts to 640x480 and hence the desktop is unusable. I am unable to select any greater resolution in the display settings. Removing Y splitter and rebooting fixes this. Does anyone know a way to fix this?

I have an ATI Radeon HD 6320 display with the 'additional' drivers from the respositroy (installing directly from ATI website made no difference). Thanks.