Not able to create new forum

No the software is not a beta, unless you have downloaded an old version.

The latest version is 8.02 and has no know issues, if there was I would know about it within hours with over 1,000 downloads per week.

The error you mention 'Variable Undefined strTxGuest' should not occur.

This variable is declared in the language files found in the language_file folder.

If you get this error it means that either a file has become corrupted during the upload process or you are using a 3rd party language files that is buggy.