Hi there mnbvczal,
I doubt that the issue you are facing is caused by the new HDD. Just to be sure of that, I would advice you to test the hard drive with WD's Data Lifeguard Diagnostic tool.
Most laptops have a safety feature of shutting down when there is something wrong with the power supply. The DC jack may be causing the problem for example. Might be a good idea to contact your laptop's manufacturer support.
WD DLG tool:
http://support.wdc.com/product/download.asp?groupid=810...
Hope this will help,
D_Know_WD