Postgres PgAdmin III Query Builder crash
We had the same problem 2 times on two different computer, in just a few days of interval.

PgAdmin started to crash each time we open query builder.

Restarting the computer, reinstalling pgAdmin with differents versions... Nothing resolved the problem. But we found the solution to this problem!

PgAdmin uses a file where it saves the last queries (kind of history) and this file was probably corrupted (or one of the queries was).

This file is in the Application Data of your Windows User, that's why reinstalling pgAdmin doesn't work: this corrupted file is common for every postgres install.

So you just got to rename or delete the file pgadmin_histoqueries.xml located in your AppData (for us, D:\Documents and Settings\XXXXX\Application Data\postgresql) and relaunch pgAdmin, this should be OK.