Error 500 - Service Currently Not Available

Hi folks,

I set up Roundcube Beta 0.1 recently - set all the options in db and main config files, uploaded the full lot, created the database - and all I get is a screen with the title "Error 500" and a big message saying "Service Not Currently Available", followed by a smaller message saying "Error No. 1f4)".

I tried looking in the logs directory inside the directory I installed Roundcube into, but there's absolutely nothing inside it. Permissions on it are set to 644 and owner as the webserver (that owner worked fine of previous versions of the program).

Any suggestions?

Thanks!

Chris