2300MP - Remote Wont Power On Device, But Will Turn Off Device ????

I have a Dell 2300MP, 30 of them in fact, but one of them is very strange. I can't turn it on with the remote control, any remote control for that mater, as i've tried others. Once the projector is on i can use all the buttons on the remote fine, except the forward/back buttons with powerpoint (but that's probably just a version problem) and i can even turn the projector off with the remote. Any ideas what causes this, it's a ceiling mounted projector attached to a DELL Optiplex GX520 Form Factor. Thanks, Josh