Can't boot into Windows 7 Ultimate with Bitlocker

will that trash my d partition ?

Was your data partition encrypted? If so I dont know if the data is recoverable. Did you try to access it using the Rescue Disks? I don't know why it would be blocked then unless BitLocker is encrypting it.

I would boot the installer, choose Custom install, use Custom Drive options to delete all other partitions besides D if you want to try to save the data. After reinstall see if you can access the data since Bitlocker will be deleted from the disk when System Reserved is deleted.

However with D remaining the installer will not recreate a 100mb System Reserved partition unless you create one first and mark it Active. But after your experience here I am guessing you may not want to mess with BitLocker any longer so I'd forget the SysReserved partition.

Another case today was posted of a USB password key not working.

This is another reason why data should always be backed up externally or to another HD. If you have the data backed up then I would wipe the HD to clear the boot sector of any protective code Bitlocker has written there.

This is all assuming BitLocker will even let you have access to reinstall. We shall see.