Screen Sharing shows red screen

Hello, I connect to several machines via Screen Sharing. All work fine except one, a mini that is at a hosting center. When I log into it the screen is red. Like everything has a red filter over it. If I reboot the mini the login screen is fine but after it's logged in again the red returns.

Anyone know what would cause this or how to get rid of it? Thanks.

I am using OS 10.5.6 and the mini is 10.4.11.