Portable GIMP won't load any images besides .xcf

PortableGIMP is unusable for me as it won't open any other file format other than .xcf and I get an "unknow image format" error on .PNGs, .JPGs, etc.

This is a known issue with GIMP (see references below), but I've never experienced it with PortableGIMP until now. I haven't used PortableGIMP since at least last summer so this bug was introduced since then.

http://www.gimptalk.com/forum/viewtopic.php?t=7749
http://www.google.com/#hl=en&source=hp&q=gimp+error+unknown+file+type&aq...

I did go check the info in one of the posts which tells you to go check Preferences -> Folders -> Plug-Ins and that was set correctly to the place they were installed to so I'm out of ideas.

Any help getting this sorted is appreciated. I need to make to picture background colors transparent and GIMP is the only tool I have to work with that can do what I want.