> I have been trying to update 2 httrack-mirrored websites, 
> httrack hangs at the very moment I pressed the Finish 
> button, the Information and Action panels remain blank 
and 
> stay there

This isn't a lockup, but a very-slow cache reading. 
Insert this option in the URL list or in the filters list:
--fast-engine

This will disable all checking routines (slow) and should 
speed up the whole process.