I've been able to play a few sieges, but for some reason i can't play another. They are concentrated in the middle east, i think that the first CTD happened in Antioch, and it repeated itself in every other city to the south that i tried.

Operating system: Win XP SP3
Kingdoms 1.5
SS 6.4
Savage AI - Permanent Watchtowers

I can't play any siege. I've been trying to assault Gaza with the Byzantines, and i get a CTD with "unspecified error" when loading. Since Antioch (as stated above) i can't do another siege. I'm not sure if it's something related to this area of the map...

Spoiler Alert, click show to read: 
12:17:44.562 [system.rpt] [always] CPU: SSE2
12:17:44.562 [system.rpt] [always] ==== system log start, build date: Feb 25 2008 version development ===
12:17:44.562 [system.io] [always] mounted pack packs/data_0.pack
12:17:44.562 [system.io] [always] mounted pack packs/data_1.pack
12:17:44.562 [system.io] [always] mounted pack packs/data_2.pack
12:17:44.562 [system.io] [always] mounted pack packs/data_3.pack
12:17:44.562 [system.io] [always] mounted pack packs/data_4.pack
12:17:44.562 [system.io] [always] mounted pack packs/localized.pack
12:22:56.375 [system.rpt] [error] Medieval 2: Total War encountered an unspecified error and will now exit.