Old bug that has been bitched-about before. At least my 3rd time it has happened in my 1.39 campaign.
Could select units but not move or attack. This with 2 enemy remaining after I had spent about 1/2 hour killing about 80%+ of them without loss.
Then auto-resolve was my only way out, and it lost. 
My army was 3 heroes with Ythil bows, plus Xander from the book content with Elementium Karrazan. Just curious -- anybody else play him recently? Anyway, that combination of mobility & non-retaliate attacks means certain eventual victory against almost anything, but it takes a long time, especially with the current high hit-points for baddies. The baddies had 5,444 hit points (Playing max difficulty with epic pacing).
The hit point change leads to longer battles and means more chance for the bug to kick in, plus less chance of autoresolve winning, plus more time lost when autoresolve looses. So the old sporadic bug is more irritating than it as in older versions. And did I say
?
debug.err http://dl.dropbox.com/u/8928343/debug-battle-freeze.err after autoresolve & exit
save from just before the battle http://dl.dropbox.com/u/8928343/QuickSave-battle-freeze.EleSav (attack princess Giexag's stack)