BOOTMGR Problems

Right,

So I just bought a new desktop, preloaded with Vista but that came with a W7 upgrade disk. Having installed W7 in a partition (D:) i then decided to make the partition which i'd installed it to active in my attempts to delete the vista partition and extend the W7 one.

However, the first boot up afterwards led me to the message 'BOOTMGR is missing Press Ctrl+Alt+Del to restart'. I only have a W7 upgrade disk which it won't boot from and I've tried pressing F8 to get to the Advanced Boot Options screen but that won't work either.

Any help would be much appreciated.

Yes, thanks Pauly, that was what the problem was,

Thanks a lot!