DVI to ANALOG on Mac Mini


Hey, I have a mac mini and orginally had it on a 23" cinema display with dvi when I installed OS X. Now I have it on a 17" lcd, but after I boot up and login the monitor seems to get out of range. How can I revert it back to a smaller resolution?
If the mini thinks it's still connected to a different display, you'll probably have to connect to that display...
I went back with the cinema display and changed all the settings to their lowest option(colors and resolution). also zapped the pram. NO LOVE.

One thing to mention is it boots fine I can see hte apple logo, its gets to the login screen and I can login, as soon as I login the monitor shuts off.

?? any ideas? I need to get this fixed SOON!!!