I have never encountered this problem using external libraries. Check out JavaWowUpdater. It will download all the libraries for you (config option) so they are always up to date. I haven't played in 2 days so I will jump in and check this change real quick. brb

Edit: Everything is working fine. I have pitbull and Multiboxer with the pitbull addin.

Note that the libraries will show up as separate addons when using externals but it really makes things easier.

Settings I use for Jwowupdater.
Uncheck - no externals
Check - split addons
Check - update if libraries changed
Check - auto embeds handling
The other options are personal preference