Computer monitor starts up and then goes black

[cothrift]

Hi all first time posting.

My question deals with a problem I encountered while trying to install a new DVD drive in my box. When I turn my computer on it goes through bios and start up, when it reaches the part were I should enter my username and password the monitor goes blank and a video message comes up that says no signal input. I am running Windows 2000 and have tried a bunch of troubleshooting but nothing seems to work.

Thanks for your help