Seems I remember our 'release' version from almost 2 years ago crashing in some cases on unban.
Are you using latest from Github?
Also, removeid should work... ULX has nothing to do with that.
If you want, attach your /data/ULib/bans.txt and your /cfg/banned_user.cfg files to your next post (using the ATTACHMENTS AND OTHER OPTIONS link below post, don't just paste them into your post box), and provide your steam ID and I'll remove your ban.
Either way, sounds like you have odd server issues that ULX isn't truly culprit of.
(Again though, make sure you're using our GITHUB latest code, not the 'release' from our downloads page)