On the 2.5-dev nightly build from 02 April 2013 on windows 7 64 Bit, the game freezes right at the start of a base defense mission.

I can select and equip my team but after the mission is loaded, the game hangs on the battlescape view. The view is already loaded and I can see a corner of the map.

This bug has been reproducible with various team sizes and even starting from an earlier save game, the bug occurs on the first base defense mission.

A relevant part of the log seems to be:

<source lang="">
...
2013/04/06 15:24:34 Not enough spawn points for team 1 (actorsize: 1)
2013/04/06 15:24:34 Not enough spawn points for team 1 (actorsize: 1)
2013/04/06 15:24:34 Not enough spawn points for team 1 (actorsize: 1)
2013/04/06 15:24:34 Not enough spawn points for team 1 (actorsize: 1)
2013/04/06 15:24:34 Used inventory slots client Philip spawn: 0
2013/04/06 15:24:34 ********************
2013/04/06 15:24:34 ERROR: Game Error: Could not find character on team 1 with unique character number 8
2013/04/06 15:24:34 ********************
2013/04/06 15:24:34 Shutdown server: Server crashed.
...
</source>

The full logfile and the savegame can be found in the forum post for this issue:
[http://ufoai.org/forum/index.php?topic=7685.0 Crash on base defense switch to battlescape]