BootMGR is Missing after Installation Buffalo(HD-PXT500U2) into Windows7

I bought Buffalo Ministation (HD-PXT500U2) last 3days and I installed it into my SonyVAIO E-series.
(Wins7HomePremium, IntelCore i3-330M Processor 2.13GHz, Hard Disk Drive 320GB/Memory 4GB, ATI Radeon Premium Graphics).

It was all in OK condition after restarting once the installation completed & then I shut it down last night after used.

But this morning when I tried to turn it on, the screen appeared "BootMGR is missing. Press CTRL+ALT+DEL to restart."

I tried the key but the restart wont turn my Wins7 to start. It was still appear the same warn.

I've search on the website about the bootmgr missing but all I found is about Windows Vista,XP,2000. Nothing about Windows7.

Is that meant Windows7 is not supporting Buffalo (HD-PXT500U2) Hard Drive or on the other way?

I really confused & teary cause I dont want my thousands file in driveC to be formatted & gone!

My friend suggested to transfer the files by take out my laptop hard drive (externally).

How to solve this? Can I recover my Wins7 without having to sweep all my files in my driveC?

Sorry a lot cause I'm not a computer + IT pro. Hope someone out there can help me get through this problem.

So you're saying you took the hard drive out of the external case and put it in your laptop? Did you just connect it externally?

How did you do the Windows 7 install on it? Did you do a new custom install or did you clone from the existing hard drive?

Some more information will help please.

Oh and by the way... Welcome to the Windows 7 Forums website! Merry Christmas!