Odd problem, login screen wont come up sometimes.

[Matt_Smi]

I normally always leave my computer running, but sometimes I shut it down or need to reboot after a software install. And I seem to have this odd, intermittent issue when booting it. The computer will load windows normally, but once it gets to the part where the login screen should come up, nothing will happen, it just stays black. I then shut the computer off and try again and it usually will come up. This seems to happen mostly when I shut the computer off completely and power it back on, not so much on reboots. Has anyone experience this before? I have a few theories, could be my video card and how I have three displays hooked into it (two monitors and a TV), maybe it gets confused about which screen to put the login on? It also seems like if I have my TV turned on this wont happen, this could be the vid card driver. Also I do have a different login screen that I changed with a program, but I have been using that for a few years without this issue on another machine.