Ok so I think I understand and I had a similar issue with my system and a 26"LCD TV which I used with ease with XP but building a new rig with Windows 7 resulted in booting up to a black screen about 70% of the time but if I rebooted often enough then I could eventually boot past it and all was fine till the next start up. I never worked this issue out even after replacing almost every component in the new rig and working with the BSOD team here. As it turned out the TV was the issue not playing nice with the standard Windows 7 video driver
and as no updated driver was available or provided by the TV Mfrgr. only upgrading to two LED monitors did I find that my rig boots perfect every time. I wish I had more details but my suggestion would be to look to a real monitor and maybe opt for one with a built in TV tuner as well.
One last trick I found as crazy as this will sound, while booting I found that buy moving my mouse at the same time the system was moving into the Windows 7 log on screen could I sometimes improve my odds . You might give that a try but in the end it was so time consuming that I went crazy and only solved it with enough spare components to build a complete new rig (mine today) and now (2) LED monitors and life is great !