Looks like the boot is not finding the Win 7 boot files. Have you changed your drives around or added a new one?
Did you remove one?
Can you boot if the Win 7 DVD is in the drive?
What else might have happened to make the active partition with the boot files not be where it should be....? You might want to download and burn Partition Wizard in case you need to use a bootable partition manager, or if you want to use diskpart command line we can do that also.