It's been awhile since this thread was posted, but hopefully this helps someone. Not a true fix, but it got my player functional.
I've been having the Unable to Replace Image error and the initialization error for a few days now. I can't think of any changes I've made to my system that would have caused this, but it's happening all the same.
Anyways, I was able to start the program with the (non-skinned) .exe in the mediamonkey folder. It still gives the initialization error but then seems to work normally, except without skins of course. Then I went into options and ticked the box for "override skin theme with windows system theme". I can now start mediamonkey with the normal .exe. The skin is still not working, so the backgrounds are all white, but at least I can start the player up now and it seems to have functionality that was broken by this bizarre error.
And before someone suggests it, no, updating does not help. Neither does attempting to change skins (just gives the Unable to Replace Image error).