The first step is a fresh install. Also, do you have anything modifying any of the files such as the new to old patch or any mods?
Its a Vanilla installation, have no desire to convert it to the older game or install any mods. I want to play it as is, I'm not fussy. I will how ever try re-installing the game, I'll have to see if I still have the installer on my HDD.
I'm almost positive the rerelease ISN'T portable... but you might be able to change your install directory to the external HDD the registry.
I have tried finding any registry values in the software hive on my HDD(I still have my OS installation on what is now my External HDD), but I couldn't find anything for it, and yes I did search under wow6432node. If you know where the re-release might also store its registry keys let me know and I'll will have a look.