Very strange.  I've played 1.5 a ton but I've only had one hang late game.  Reloading the auto-save avoided the problem.  It must not like certain PC setups.

I have the same problems as the OP. The game has become completely unplayable. 

I never had any problems in 1.3 (or older). 1.4 saw some crashes. 1.5 is horrible: lots of freezes.

I have Out of Memory problems on save game and on the end of turn (the same turn it happens with saving when I try to just continue) on large maps (on standard scenario, too) and there is no way the game can be continued even loading a previous save (it happens again). 32-bit Windows XP here, no mods.

I came to the conclusion that the game really pushes the limits of the videocard....I think it was partly to blame for my old card's failing (that and the fact that it was a 7 year old card that played max graphics on everything I touched....I'm not kind to my cards). I had many game hangs and crashes prior to the Christmas break on my old system.

Over the holidays I upgraded from my winXP 32-bit to a win7 64-bit OS on an SSD drive. Also tossed in a new videocard : A Nvidia GT 640 ... it's nothing special, but it had to be compatible with the rest of my computer, as it's still 7 years old: ASUS P5K board with dual Intel 3gig/3gig processors and 4gigs of Corsair ram.

Since, I've plugged in over 100+ hours in LH 1.5 without a single crash or hang. Considering some of the other theads I've posted on the previous instability of the game, I was quite pleased in the quality improvement. (I'm also glad I FINALLY get my pedestrians back)