Yeah I've just run into a similar problem, I modelled a small, simple infantry mech in MilkShape3D (latest version too, 1.6.6a) and animated the legs, exported a .x file and got similar problems to MasterInsan0.
MS3D has 2 exporters for .x files, one by Matthew Scott and one by JT. If I just do a straight export on Mr Scott's and don't change any options (export meshes, materials and anims, lock root bone for anims, Frame Offset 1), DBP refuses to even deal with the resulting file, it just drops back to the editor when it tries to load it without so much as an error message. JT's exporter is more successful, DBP will load the file and a CHECKLIST command shows the joints from MS3D have been loaded as limbs (which I want), but there's no model visible. If I remove the joints and export just the mesh, it appears fine, but of course has no animation. Soyuz, you mentioned something about that mate, got any ideas?
I'm currently trying to load the mesh from one file and append anim data to it from another file, but it's still not working. The joints need to be in the mesh file for it to work, and they seem to be the problem. As MasterInsan0 says, it looks like MS3D may be incapable of doing the anims properly, unless anyone out there knows something...?
By the Great Wolf... it actually WORKS!!!
Gimme Fuel Gimme Fire Gimme That Which I Desire!