This bug only affects you if you have no forums, but do have categories.
on line #383 find the following:
for iForumCheck = 0 to recForumCount
if CatID = allForumData(fCAT_ID, iForumCheck) then bContainsForum = True
next
and replace it with the following:
if recForumCount <> "" then
for iForumCheck = 0 to recForumCount
if CatID = allForumData(fCAT_ID, iForumCheck) then bContainsForum = True
next
end if