4560 not booting from bootcamp after update

[rexxmagnus]

I've recently upgraded to build 4560. Haven't changed anything in my configuration, but now it's not booting from the bootcamp partition that I used before.
Starts up ok, but after the usual 'bios' screen and then momentary flash of the boot menu (shows parallels and standard windows xp) the screen stays black. No disk activity is evident in the status monitor.

Log files show:

bootcamp.log:
[12.08.2007]-[10:44:27.187]: find_bsd_win_parts: Win partition disk0s3 is not removable
[12.08.2007]-[10:44:27.249]: find_bsd_win_parts: Win partition disk0s3 is not removable
[12.08.2007]-[10:44:27.253]: Open: use default partition "disk0s3"
[12.08.2007]-[10:44:27.253]: Open: connected partition disk0s3
[12.08.2007]-[10:44:27.874]: find_bsd_win_parts: Win partition disk0s3 is not removable
[12.08.2007]-[10:44:27.877]: Open: use default partition "disk0s3"
[12.08.2007]-[10:44:27.877]: Open: connected partition disk0s3
[12.08.2007]-[10:44:31.037]: MakeMbr: adding to mbr partition (172638248, 22733280)
[12.08.2007]-[10:44:31.038]: carbon_unmount_vol: unmounting volume XP


BootcampOSP.log:
[12.08.2007]-[10:44:32.041]: extract_system_root_path() directory: WINDOWS
[12.08.2007]-[10:44:37.337]: reg_backup_keys: key "Microsoft\Windows NT\CurrentVersion\WPAEvents", value "LastWPAEventLogged", value not found

Leaving it standing a couple of minutes before quitting and then...

[12.08.2007]-[10:47:06.454]: extract_system_root_path() directory: WINDOWS
[12.08.2007]-[10:47:09.105]: reg_backup_keys: key "Microsoft\Windows NT\CurrentVersion\WPAEvents", value "LastWPAEventLogged", value not found
[12.08.2007]-[10:47:09.105]: reg_backup_keys: key "Microsoft\Windows\CurrentVersion\Run", value "Apple_KbdMgr", value not found