Hmm.. Only thing I can imagine is there has been some kind of mix-up between FH and FH+ folders, due to similar names between the folders etc.. Causing your pc to get confused.
Go through all of your FH folders and if you remember what you downloaded for FH+, look to see that there are only FH folders in there.. Otherwise you might have to simply resort to re-downloading the game. And make sure no FH+ files, especially code stuff and textures, mistakenly land in your FH folders.
Of course, it's hard to judge the situation with the amount of given info.. Hope I was helpful XD