The Lost Post - help please

I tried to post on 'Snagging List' yesterday morning with a small picture included.

The post hasn't appeared and after that I couldn't seem to post anything on this or any other thread.

Perhaps someone could enlighten me as to what I might have done wrong yesterday morning.

I tried again this morning and this afternoon with no success but this attempt seems to be working.

Every time I tried to post I had this message in red -

'There was an error submitting the form. Please ensure all required fields are completed and try again - Internal Server Error'