Ok I accidently lied yesterday and I realized it when I did some more testing last night.
When I have the J-Pac hooked up I'm not getting the Windows chime on boot up...though I can see in Split Screen mode that it's getting past POST and loading Windows...it's just like when Soft15khz kicks in while attached to the J-Pac it keeps windows from booting.
Oddly enough though I seem to get the same results when I start the computer without a monitor at all or when I plug a cable in with nothing on the other side...so it's like my Video card is detecting that there isn't a monitor there and somehow keeping windows from loading.
I'm not sure why the computer doesn't seem to think that the J-pac behaves the same as a monitor...but I'm gonna play around with the BIOS and video card settings tonight to see if I can't disable whatever it's trying to do.
As a long shot, Check your monitor cable and see if any pins are broken. It almost sounds like your test monitor may have a broken pin.
You said it was a crt so its probably got some age on it.
I have the same problem, but with a different setup. I have a hybrid monitor that can display 640x480 and lower only. Thankfully, (with a test monitor,) i was able to force windows to 640x480 with the nvidia drivers. But my bios and my boot screens wont go any lower than 800x600. Never have been able to fix that problem.
also, before that, my test monitor also would not work. Turns out it had a broken pin.