I've had a similar issue for a long time too, but only with FSWXR2100 equipped aircraft. Never found a fix that worked. I just accept it now since though annoying, it really has no other ill effect.

Guys, check your FS2004 root folder for a gdiplus.dll There is an addon which puts an old version of this dll where it's not supposed to be, resulting in most other addons which depend on this dll to fail.regards,Oleksiy