Originally Posted by
Honorbound
7 chars on that account, that means you can create one more, right?
In that case, rename the current Prefs folder again, remove any 3rd party/custom stuff you might have, GUI, maps, scripts, everything. Basically, strip down the client to the state it should be after a fresh install. Try to log in on any of the non-affected accounts to make sure the client itself works, then delete the new Prefs folder which was created during this test login.
Then create a new temporary char on the affected account and try to log in. If it crashes, it has to be some damage to the account on server side no matter what that specific GM said. Petition again.
If it doesn't crash, try to log in with all of the other chars on that account. If any or all of them still crash, they must have something in common, like all possessing one specific item, being in the same zone/instance/area, having a certain buff running on them, etc. Something that causes the client to crash when it tries to apply/display/whatever something specific to those chars only; which may result from some client side database corruption with a very limited scope. Or, it still could be damage to the account affecting the chars created earlier, but not the new one you've just created.