Hi Arno,
Both http://senseis.xmp.net/?UnsolvedProblems and http://senseis.xmp.net/?diff=UnsolvedTemplate resulted in the same error:
Fatal error: Class 'SearchTemplate?' not found in /home/www/senseis.xmp.net/private_html/lib/transform/specialpages.php on line 126
Apparently tapir was trying out something, but triggered some bug instead.
I wondered that the added unsolved problems didn't show up, added an additional "unsolved" search request beneath the "Unsolved" request. Later I undid the unsolved template page, but those search requests still fail.
I feel so incompetent. I can't solve those problems, but even fail flagging them as unsolved... ;)
I'm getting this error on Unsolved Problems right now, was it not resolved or has it come back?
Thanks for the report.
You may have to force a reload on the page to see the bug disappear.