If it's a S.M.A.R.T drive then there are some applications which help you keep an eye on HD health. As for not been able to boot some time, it could be for many reasons. From loose connection to corrupt memory locations in the RAM. Also try avoiding turning your laptop on below zero degree C, since although the harddisk surface itself is in closed environment, but the connections are not. And condensation may demage those fine connections.
I just tried pcdiag ultra lite. The read/write functions were fine.
Can you suggest a good tool to see if the connections are ok?