Black screen if booting Windows or from Windows Install DVD

Hi,

I had a working Windows 7 x64 Pro Boot Camp setup until recently. Now, when I attempt to boot from the Statup Manager, I can select the Windows partition but it simply sits at a black screen indefinitely. I attempted to set the Windows partition as the Startup Disk from the System Preferences, but it doesn't appear. I've attempted to boot from the Windows 7 Installation DVD in order to perform a Windows Startup Repair, but that black screens in the same manner as the Windows partition.

Here's the result of sudo gpt -r -vv show disk3 on the relevant disk:

gpt show: disk3: mediasize=500107862016; sectorsize=512; blocks=976773168

gpt show: disk3: Suspicious MBR at sector 0

gpt show: disk3: Pri GPT at sector 1

gpt show: disk3: Sec GPT at sector 976773167

start size index contents

0 1 MBR

1 1 Pri GPT header

2 32 Pri GPT table

34 6

40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B

409640 156303528 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

156713168 1269536

157982704 659841040 3 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

817823744 262144

818085888 158687232 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

976773120 15

976773135 32 Sec GPT table

976773167 1 Sec GPT header

Here's the result of sudo fdisk /dev/disk3 on the relevant disk:

Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: EE 0 0 2 - 1023 254 63 [ 1 - 818085887] <Unknown ID>

*2: 07 1023 254 63 - 1023 254 63 [ 818085888 - 158687232] HPFS/QNX/AUX

3: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

So far as I can tell, this means my hybrid MBR setup is intact, but I could be wrong. I should point out that this drive doesn't actually contain a bootable OS X partition, which exists on a completely separate drive and boots just fine.

Anyone able to assist?