500 Internal Server Error

[#1]

Since the weekend before last I have been experiencing a strange problem with a forum that I am Admin on. It all started at the time I had connection issues on the Sunday. The forum runs under phpBB and is hosted in the States. When I try to edit a message or make  along post I get the 500 Internal Server Error. I have spoken to the site owner and he does not have  a problem at his end. This I have a tendency  to agree with as if I used my log in from work (literally 1 minute from home, so the same cables, etc but different ISP) I can edit and post without issue. I have tried using several PCs at home, creating a new account, etc. However as long as I used a PC at home I have this problem. So this leaves me with the common factors, Router & ISP.
I did try Plusnet Customer support but unfortunately I don't think I explained myself very well to the rep as all he could do was suggest I run the BT speedtest (which by the way never gets past 96% each time I try it). He did created a closed ticket saying that he had informed the eu to perform speed tests.
I am only having this problem with the one site and it all started with the connection issues so instinct says that the problem is interlinked. Any suggests as to what to investigate next would be much appreciated.

[#2]

Glad to see I am not the only one baffled by this problem which is still on going :(.

[#3]

And the url is? 

[#4]

hi
You get the "500 Internal Server Error" message when you try to run a script with problems or a script that is not fully supported by the web server

First thing to do is to identify when this happens and try to locate the common code for this event that might be causing the issue

[#5]

That's the problem it just started after a connection issue at my end not the server end. Then running exactly the same script from a different location (work) no problem either. The site owner is trying to get to the bottom of the issue. I just can't get my head around the fact an edit I can do from work I can't do from home less than 100 yards away. The only think it could be linked to is my IP address, but stumped why it would allow me to make short posts not long posts.
For those interested in the url it is www.dansego.com/folderol/forum.

[#6]

sound like a data transmission problem, but still too early to judge :S
if you are sure that the logs on the servers shows no problem. I would suggest changing the MTU and trying another browser but before that you can try another computer or laptop if you can get hold of one for testing and wire it into your broadband modem/router.
this is to eliminate any problem with the connection or the IP.

[#7]

I recently change the MTU down to 1430, but still no change. This is the DrTCP figures that I am currently using on my main PC.

[#8]

Did you also change the MTU value on your router. Just setting it on your PC may not have made any difference.

[#9]

The router is set to Auto so thought this would take care of it.
[Edit] I have just set the router manually to a MTU of 1430 but still get the same error.

[#10]

I tried accessing http://www.dansego.com/folderol/forum with a fake signon.
It didn't say there was a 500 error and I assume signing on requires db access?
Searches also work.
BTW MTU=1500 and quite a zippy connection.

[#11]

Yep, everyone else (except the wife) can connect with out issue. Even if I create a new username I have the same issues from from.

[#12]

Hi,
Just PM'd you with a link to my proxy. can you try to login and post on your forum using the proxy link I've supplied. this will eliminate any browser issues or cookies and even IP as the proxy that I'm running is hosted on a US-Based server

[#13]

Thanks for that I will try it out now and post the results here.
[Edit]
Prior to using the proxy tried add a # to the title of my test thread. I got the 500 error. However when using the proxy the amendment posted without issue. PM response sent RamiDoodle.
Just deleted the cookies and still getting the same problem when I direct connect. Think it is time to try a 3rd browser.

[#14]

Any update with the alternative web-browser 

[#15]

Just completed the same test using Opera and still got the 500 Error.