After leaving my screen resolution on 1024x768 for a long time, I decided to change it back to 800x600, but when I tried the screen just flickers off. Even though I know I could use 800x600 before, I went to check my video card's compatibility, and it does support 800x600. I don't know what else to do, please help.

Are you using the same monitor as when it worked correctly at 800x600?

Try using 16 or 256 colours to see if that works.

Try changing the refresh rate to 'default' or 60Hz.

Yes I am using the same monitor.
I tried switching to 16 bit or even 256 colors.
And my refresh rate is set at 60Hz.

I think it maybe that I switched a new video card, but I checked the card'd compatibility and it supports 800x600.

Strange. Are you sure the drivers for the video card are still installed correctly? You can check this by going into Control Panel > System > Device Manager and looking at what's listed under Graphics Adapters (I think that's what it's called). What is the graphics card listed as?

Does it run correctly on 640x480 resolution?

If there's a refresh rate listed as 'Optimal', try that - Windows will decide the best refresh rate that it can get to work (if any).

Let us know

I'm not sure what you mean by installed correctly. If you mean that it displays the "This software is running correctly." then yes it is installed correctly.

My monitor can't even go below 800x600, much less 640x480.

And no there is no "Optimal" refresh rate.

I've only had this problem before because I seem to went higher then my video card compatibility, but now I'm having problems because I'm going too low.. It is very confusing.

have you checked all the settings via Control Panel > Display > Settings > Advanced ? & or > Troubleshoot ? are you rebooting after change? or have you switched off that setting?

Yes I checked all the settings via Control Panel > Display > Settings > Advanced & Troubleshoot.

No I'm not rebooting after change because I turned that feature off. It automatically applies new settings without rebooting.

update your video driver

if you have older video card or anyother extra video card install it and if it still gives you that problem maybe its not a problem with your video card or driver maybe to do with your monitor, try using another monitor...

i decided to scrap the monitor and buy a new monitor. thanks for you help though.