Search problem – headers

Ok, im having trouble with my search function. When i try a search, i get this message.
Cannot modify header information – headers already sent by… (the rest removed for security issues)
Anyway, the only modifications to the admin i made is once when i couldnt login. I found a topic on the forum that changed some lines in my login page. I have no idea whats wrong, can anyone help?
http://www.un-advertised.com/coire/