Just to verify, I don't mean to sound like a broken record player here... (I swear it sounds like a profile bug)
You uninstall Lifetank via the Control Panel. Then you browse in My Computer for C:\Program Files\Lifetank X and C:\Program Files\Darkside Softwares and you delete those two directories completely. Then you are reinstalling Lifetank via our file.
It is a known (unknown?) issue that when you install/reinstall LT on top of a previous installation, somehow the Profiles tend to get corrupted and the plugin starts doing some odd/unexplained things. I haven't seen or heard of anyone else having this type of problem which tells me it's only affecting you, and the only difference between you and everyone else are your profiles. Profiles are also saved based on Character name and server, which could be why it works on some toons or even another server and not others.
C
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