Rename it to 'IMG1944' [with its suffix] and try.

Being able to upload on Facebook is irrelevant.  This isn't Facebook...

There's two separate issues in this thread, the avatar issue is most likely not related to the comment issue.  In the future, it's easier to keep track of an issue with a separate thread.

I'll do testing today with the avatars and see if I can reproduce the issue.

For the commenting, adblocks are such are nearly always the cause.

One other (less pleasant) possibility is having a virus which interferes... but that's less likely. BTW, even if you scan with 2 AV's (better to scan with 5 - online scanners), you still might miss some.

Rather than whitelist anything, I just disabled all my extensions but still can't post a comment to a skin.  Behavior when left-clicking 'Submit' is the same, just jumps to the top of the page without 'submitting'.