Lovely mod man
"but why does it always work when a video game is on?"
When you are playing a game, chances are good its a Directx game and thus when running fullscreen there is absolutely no drawing of opengl subsystem like windows desktop.
This is why you notice massive frame rate drops when running window mode games. it is drawing both Dx and opengl. The projector isnt doing anything wrong, its the same as a monitor, it can only display what it's given. it cannot simply create graphical glitches like u describe. My thoughts would be the upgrade all drivers, and possibly look for hardware errors under device manager.
The most important thing to remember here is that with most standard CRT monitor there are two "profiles" stored. One for opengl and one for directx, and you will see which one you are in if you open your monitor menu while in a game, etc it should say Directx preferences, etc. This doesn't change the output obviously but if your monitor is incapable of showing a certain res it will automatically stretch it out or something. If your projector is the same way, then its likely you just need to manually tweak screensize, and depth manually via the projector's settings so both modes match. this will minimize the "video mode switch" issues i think. One other thing is if your opengl mode is not set the same as your dx mode the video card will still try to stretch, expand, squeeze and basically do everything it can to force the mode to work on the output device. this is generally the worst cause for errors because at this point its not your hardware simply sending data, its software telling it to tweak it first. you can probably imagine problems would arise from this. My best input here would be to tell you to also hook up a monitor to see what that displays.
My idea: its your video card not built well for switching video outputs. My ATI Radeon All in wonder 9800 pro was the same way. it would just not work sometimes for no reason and other times i ended up with a blank monitor and TV screen, forcing a hard reboot because i couldnt see anything. There are tons of other ways to get video signals out of computers though so i wouldnt worry about it. try everything u can then look for an alternate card or option.
hope i helped a tad.
EDIT: also just a side note.. im running an ATI FireGL V7100 which is powering my Apple 30" Cinema HD monitor @2560 x 1600 and i can tell you that if i try to run a window mode game on this monitor at this desktop res the frame buffer is somewhere around 200 megs for a single frame. its drawing both systems on all of these pixels. so its using just about all of my onboard ram. If i take a screenshot of CounterStrike: Source running it at 2560 x 1500 it crashes me to desktop everytime. i simply run out of vram. if you run a HD projector it may just be running into graphical errors because of this buffer. i used to have a simple frame buffer calculator on the web somewhere.. if you are running 1920x1080 (1080i) res with antialiasing on 2x on both opengl and a DX game windowed its like 180-200 megs or something. Just thought perhaps this might help. the processor of the GPU isnt always the most important thing to remember. its onboard ram does have limitations. if your output res is lower than this it sounds driver level to me.
"but why does it always work when a video game is on?"
When you are playing a game, chances are good its a Directx game and thus when running fullscreen there is absolutely no drawing of opengl subsystem like windows desktop.
This is why you notice massive frame rate drops when running window mode games. it is drawing both Dx and opengl. The projector isnt doing anything wrong, its the same as a monitor, it can only display what it's given. it cannot simply create graphical glitches like u describe. My thoughts would be the upgrade all drivers, and possibly look for hardware errors under device manager.
The most important thing to remember here is that with most standard CRT monitor there are two "profiles" stored. One for opengl and one for directx, and you will see which one you are in if you open your monitor menu while in a game, etc it should say Directx preferences, etc. This doesn't change the output obviously but if your monitor is incapable of showing a certain res it will automatically stretch it out or something. If your projector is the same way, then its likely you just need to manually tweak screensize, and depth manually via the projector's settings so both modes match. this will minimize the "video mode switch" issues i think. One other thing is if your opengl mode is not set the same as your dx mode the video card will still try to stretch, expand, squeeze and basically do everything it can to force the mode to work on the output device. this is generally the worst cause for errors because at this point its not your hardware simply sending data, its software telling it to tweak it first. you can probably imagine problems would arise from this. My best input here would be to tell you to also hook up a monitor to see what that displays.
My idea: its your video card not built well for switching video outputs. My ATI Radeon All in wonder 9800 pro was the same way. it would just not work sometimes for no reason and other times i ended up with a blank monitor and TV screen, forcing a hard reboot because i couldnt see anything. There are tons of other ways to get video signals out of computers though so i wouldnt worry about it. try everything u can then look for an alternate card or option.
hope i helped a tad.
EDIT: also just a side note.. im running an ATI FireGL V7100 which is powering my Apple 30" Cinema HD monitor @2560 x 1600 and i can tell you that if i try to run a window mode game on this monitor at this desktop res the frame buffer is somewhere around 200 megs for a single frame. its drawing both systems on all of these pixels. so its using just about all of my onboard ram. If i take a screenshot of CounterStrike: Source running it at 2560 x 1500 it crashes me to desktop everytime. i simply run out of vram. if you run a HD projector it may just be running into graphical errors because of this buffer. i used to have a simple frame buffer calculator on the web somewhere.. if you are running 1920x1080 (1080i) res with antialiasing on 2x on both opengl and a DX game windowed its like 180-200 megs or something. Just thought perhaps this might help. the processor of the GPU isnt always the most important thing to remember. its onboard ram does have limitations. if your output res is lower than this it sounds driver level to me.