I've recently set up Ubuntu 7.10 to use an external monitor, using xrandr and a virtual screen entry in xorg.conf.
This is all fine and good, and everything works (laptop screen is at the correct res, external is too), except when I try and play videos.
When I load one up, it starts playing with a blue screen. There's sound, but no picture - just blue. I'm using VLC for this, but it happens with MoviePlayer and MPlayer too, so it must be one of the libraries. The weird thing is, it only does this on the external monitor. If I move it to the internal one, everything plays fine. If I put half on the internal, half on the external, the half on the external is blue, but the half on the internal monitor displays fine. Though on a second look, it only works if less than (or equal to? Not sure) half is on the external monitor. Otherwise it displays the last frame, but keeps playing the audio.
If I open a second instance of VLC (which actually opens two more, for a total of three - probably a VLC bug?) by double-clicking on the file, it plays just fine on both internal and external monitors. If I close the currently running instance, then open a new one, it does the same thing - I have to open the movie again while there's an instance of VLC already running.
Anyone know what's going on here? It's technically the same desktop across both, they're just on different monitors. Could that be the problem? I don't know if I want to hack around with my xorg.conf file to get two proper desktops - that seems like a lot of work, and what I have now basically works, except for this.