EVH D-Tuna

Does anyone own the D-Tuna. I do and its driving me up a wall. Everytime I bring it back up to E, it throughs the other strings out of tune. Either I'm doing something wrong or it just plain sucks. HELP!!!!

This is just a guess of course, but here goes.
Eddie uses this system on a floyd rose type trem, however, he does not have a cavity in his guitar. The trem just rests on the body, which means you can loosen a string, without messing with the others strings tuning.

I assume you are using a guitar WITH a cavity for the trem. So, maybe this is the problem?

This is just a guess though. Anyone correct me if I'm wrong.