Guild Wars 1 - What changed since yesterday?

So, yesterday I reactivated ISBoxer to box some in GW 1.

I set it up, using 2 folders and 2 games in IS - I plays fine on one computer (well as fine as a game with no follow plays).

Today, I get home - Try to launch the same character set that ran fine yesterday - And IS fails to "hide the second GW from the first" I get the same error message (from guild wars) that I would if I tried to run the game myself by double clicking twice on it (basically the second EXE cant write to a DAT file in the first EXEs path - as the first EXE is using it).

Any ideas?

If I for some reason can't get IS to launch 2 - Can I launch a tool like this and still do its magic?: http://code.google.com/p/gwmultilaunch/ (a open source software that launches multiple copies of Gw1)?

Still soooo confused as to how it worked last night but not now

Fixed it by pre-running a registry import

Still completely clueless why it's needed as it worked yesterday

I'll post a guide in a separate thread in a minute, with all the reg keys etc.