Long time ago I was trying to update to 7.3?? and my installation was crashing. I had to manually update it. Someone on this board posted how to force an update and I just saved it as a reference in my astaro tweaks files So all the credit goes to the original poster.

I am assuming that your up2date files got downloaded and installation was corrupt.Try running this command on console/ssh as root. No promises but it might do the trick