I can reproduce, 100% of the time, a CTD each time I attempt to craft a weapon higher than +2 Is this issue known ?
Sometimes if the weapon description is too long I think that will happen, so you could try shortening the name. Example: longsword +1 +2 +3 you can change to longsword +3 instead. in the weapon description
It could also be due to exceeding the EEL limit - I think I remember that causing a guaranteed CTD. What other enchantments do you have on the weapon?
Maximum EEL should be 10 as per the core rules. you used to be able to craft upto EEL 12 then it'd be really cheep and make you gain XP for going over... that got fixed. The weapon's name should remain short, a "Keen Masterwork Bastard Sword of Flaming Burst, Shocking Burst, Icy Burst, Smiting and Cleaving +1 +2 +3" would almost certainly cause a CTD, naming it "Death to All" wouldn't.