Are you plugging the 2.5" Laptop HDD into the desktop computer then installing windows 7 form the desktop computer onto the 2.5" laptop HDD then plugging it back into the laptop?
If so then the drivers it installed with and hardware it originally configured itself with wouldn't be compatible and its most likely BSOD to stop any hardware error, Can you list the BSOD so we know what error we are dealing with here?
Also you if you have a 4GB usb drive you could use that to install windows with onto the laptop. http://store.microsoft.com/help/iso-tool
I install my windows from USB these days as i no longer have a working disc drive in all my computers.
As long as you have a Legit Windows Key You will be fine installing from USB flash drive.