|This is caused by another program briefly taking control of your computer, causing the game to lose its palette. Almost always, this program is an anti-virus. Look at the icons in the lower right of your Windows screen and find the one for your anti-virus program. Right click on it, and you will find an option to disable it. You can re-enable it after you play.|
If disabling that doesn't let the game run in normal colors, it could be another program. Go back to those icons and try to figure out which one might be running periodically, and shut it down or disable it. Do this one by one until you find one that lets the game work right. Once you know which one it is, that's the only one you'll need to worry about in the future.
If you can't find it in the icons, then it is something that runs in the background without an icon. That will be harder to find. We may be able to help you though, if you contact us.
Oh, and of course the most likely culprit is something you're actively running! Try shutting down programs you have going before you deal with background stuff. But most programs will play nicely. I always have dozens of programs sitting around my desktop while I play.