This is a page describing how to get support.
There is a now a troubleshooting forum at the official forums (in addition to region and operating system specific forums).
Another common way is to subscribe to the users mailing list and post your question there.
If you have an IRC client program, and know how to use it (that's beyond the scope of this document, you can visit the MythTV users IRC channel at irc://irc.freenode.net/#mythtv-users
It's faster: if there's someone around who knows what is causing your problem, you might be able to get an answer instantly.
There may not be someone around who knows were your problem is coming from.