I had the exact same problem, and it's caused by a bad Hex edit job, which is caused by a worse hex edit tut by somone who will remain nameless, it screwed up my quests, fux0red the guards and destroyed the save function, re-do your morrowind.xbe, but only change Z:\data files and z:\meshes, works fine, mods load, no busted game.
as for TESDK, you should only need morrowind for the version matching feature.
hope that helps.