By the way, I was having this problem with my Zoneminder 10.04 headless server as well.

The main difference with my setup is that I do have a kvm switch hooked to it, for when there are odd issues. The only time it would lock up was when the KVM wasn't set to the server.

Intel Core 2 Duo, with Intel Integrated graphics chip.

Hopefully the nomodeset command will help on mine too!