bootcamp partition readable but won't boot

Apologies if this has been asked and answered already, but there are 298 threads to search through!...

MacBook Pro, 17", 2009, 8GB. Pre-installed with Leopard when bought new.

1. Soon after buying, I created a second partition, installed Windows 7 on it, and everything worked a charm. Dual-booting with ease, and I also ran VMWare Fusion successfully for a while, but had to abandon it.

2. Upgraded to Snow Leopard. Everything still worked fine.

3. Upgraded to Lion. Everything still worked fine.

4. I developed a need to downgrade from Lion to Snow Leopard (for reasons not relevant to the problem) but could not find an easy way to do it.

5. I used Disk Utility to split the Lion partition into two pieces. I installed Snow Leopard on the new empty partition. Snow Leopard now works. Lion now works. From both Snow Leopard and Lion I can see the Windows partition, and I can browse and open files on it. I can run Startup Disk in either OS/X and it offers me the option to start-up using the Windows partition.

6. When I try to boot into Windows, it fails to find a bootable partition. If I use Disk Utility, I can see the Windows partition, and if I ask it to Verify, it says "Verify volume failed - Invalid request". Finally, if I use Spotlight to look for BootCamp Assistant (per your introductory sticky), it can't find it. In fact it does not even find anything if I look for BootCamp>

Any suggestions, anyone?...

It sounds like you need to repair the Windows partition in order to make it bootable again. It's likely the Windows 7 boot sector has somehow gotten corrupted or the pointer file no longer points to the correct partition.

Try these instructions. Note you will need your original Windows 7 DVD. LINK