It is possible to delete imported address with private key from encrypted wallet without entering the password. I dont know how this is possible - it shouldnt be that way. The private part of wallet should be encrypted so it should not be possible to mess with it without password.
It will not hurt the wallet's consistency to delete an entry in full, whether it is encrypted or not. However I'm not sure this can be done from our UI. If it can be done, then it is a mistake on our part and we'll get to fixing it right away.
0.90.99.40-test did the trick. I can now open my wallet with many multipool inputs and it does not crash. I did not do a factory reset - just installed the testing version over 0.90. I did have to manually point Armory to Bitcoin Core 0.90, I'm guessing because I installed the 64-bit version.
First of all, 0.90.99.4 (essentially it 0.91-beta RC3) uses different LevelDB system parameters, so we highly recommend you wipe your current DB and rebuild it. As for finding x64 version of 0.9.0 bitcoin core, it should find it on its own. Empty the path input line in the settings file, restart Armory and it should find it on its own. Let me know if it doesn't (it does work just fine on my end).