I have OC 1.5.1 installed and running. Have set SEO URL's enabled and have .htaccess file in my public_html folded where the OC files are located.
As I try to open specific category or info page I get the following error:
"Not Found
The requested URL /about_us was not found on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request."
Can anybody tell me where the problem is? I have read forums all afternoon but I can nowhere find the answer....

Thank you in advance!
P.S. http://imania.bg/ is the store URL..