cannot boot from the HDD , but when it is plugged as a secondary hdd i do can see his content

Yax1

Honorable
May 11, 2013
7
0
10,510
so ..
i am trying to turn-on my pc and when it comes to the windows (windows 7 btw ) loading it's start to load and then just stop and i get black screen and the pc restart himself after a few seconds .
important thing to say it's - when i am plug this hdd to another pc i do can see the files and folders he has but still can't boot from him :S .

any thing ???? please ..
thanks in advance =] .