[eluser]marcin_koss[/eluser]
For now I removed all the rules from htaccess and I don't get that error enymore.
The problem with browser quitting loading one of the controllers still persists. It works fine on a local server.
That page basically takes all the order information, customer info, items list, prices from session variables and populates a table.
I just found that if I echo some random string in a certain place in this controller the page will load displaying all the data correctly.