I was visiting the forum (and there were only about 3 other users on it at the time), one user was uploading images...
and then I saw a 505:
Resource Limit Is Reached
The website is temporarily unable to service your request as it exceeded resource limit. Please try again later.
The host was great (Clook...they use xenforo), they also gave me more information:
It actually looks like the PHP limits were hit while uploading a Flash attachment from <ip address> at about 9:30.
(It's a shared host, I've contacted them and they have now increased the post_max_size from the default of 8M to 16M)
It sounds like the image conversion can cause processor spikes,is there anything that can be done for that now?
The increase in post_max_size might have fixed this issue for me for now, but I think others might also run into this