Resize them so that they're less than 100kb and save them on your desktop, not to the library (i don't even know what this library is!). Then you should be able to upload them from your desktop and post them.This is what i do and it works every time.
I did try to post from my desktop but it didn't help. The "library" is a PS thing. It's the collection on PS of all pictures I've uploaded in the past. Anyway, slg47 and Dreamer_D helped to upload the pics for my other thread so I suppose this isn't a big deal any more. I've also let the administrators know.