Try booting into Safe mode
This will not load any 3rd party additions, it will load some more conservative Apple drivers (may cause screen flicker), and it will clear some kernel caches (a cache is saved data in a form that can speed up a program, but is totally redundant to the original source, and thus can be safely cleared). Booting into Safe mode is just an experiment, but can often times eliminate any 3rd party interference, or a cached item out-of-sync with the world.
As for the photos, the forum does not take any format. I think the forum accepts .jpg and .png (I know I had a TIFF once and it would not take it; drove me nuts until I figured it out 🙂 ). Also size may be an issue. A full resolution 12Megapixel image may be more than the forum wants to accept. Try reducing the image size.