4
<{$xoops_module_header}> Basically this needs to be added to your theme (which I believe it is in your case?)
Otherwise... I think you may need to remove cached files (remember to keep index.html in the cache directory of course
) and perhaps regenerate the templates - as they'll have changed from the old newbb ones.
(This is only from memory, but I believe it's the common solution)
Standard "backup before you change anything" advice of course