[Typo3] indexed_search: weird malfunction (help!!)

[P H Vetch]

Hi,
 
I'm working on a TemplaVoila site on 3.8 with the latest indexed_search on a
Linux box.  For some reason, not only does the indexed_search plugin not
work, it also interferes with page generation on the page the plugin is
inserted:
 
http://qedst-43567-001.dsvr.co.uk/gilliebolton.com/search/
 
(pages should look like:
http://qedst-43567-001.dsvr.co.uk/gilliebolton.com/)
 
 - you can see that the default page head stuff is not being loaded in.  The
indexing IS working, however, and the default indexed_search CSS is being
inserted (which you can see in the source) - but no plugin.
 
Anyone got any ideas why my search plugin is not working?  I'm using an
identical setup on a Windows server with not problem at all.
 
Thanks!!