Hi elevation-
That error message means that the UBB found a corrupted file in one of your forums. A zero-byte file is a completely empty file. This means that the topic it represented is no longer available. HIstorically, this kind of thing (corrupted files) happened most when there was no available space on a server.
Regardless of the cause, the way to solve the problem (prevent this error), is to delete the file in question on the server. In the example you listed, you would go into your Forum1 directory and delete the file called "000505.cgi" (do not delete any other files!).
For instance, if your error message said, "Tried to open zero sized thread 000344 in forum 5 at e:/domains/elevationstation.co.uk/user/htdocs/cgi-bin/ubb_lib_files.cgi line XXX", you should delete file 000344.cgi in Forum5.
Hope that clarifies.
Ted O'Neill
CEO, Infopop Corporation
