Check the format and location.  It's been a while, but I vaguely remember getting something like that when I tried to post an image that was too large.  It seems to be a generic message. 

I'm having the same problem here
 
I've tried in IE8, Firefox and Chrome and I get the same error as the OP.
 
What an unprofessional piece of crap this forum software is. And what a pisspoor advert for a so-called 'serious' software company.
 
If guys like us are singularly unimpressed by it, imagine what it looks like to a prospective customer
 
Not good.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
I'm still going to purchase my CA-2A T-Type Leveling Amplifier upgrade though
 

I had the same issue w/ Safari for as long as I can remember. Firefox seemed to work. Haven't tried it recently though.

The forum has been buggy here in the last few days.

I noticed that the Harmony Central forums have shiny new software. I don't use it but it looks nice.
I tried to see what it is but I can't seem to see a label on it or a webmaster link.

J

I see the 500 error sending PMs which still go through apparently so apologies to all of you that have received the same PM several times.

The other thing I don't understand is if I try and change something in my personal information I get the "signature maximum" which I'd understand had I actually changed my signature but it's complaining about the same sig I've been using. 

I agree that the forum software is need of being put to death some TLC.