Well, posting the error would have been more helpful. I thought you meant that it returned crappy results, because SMF almost always returns crappy results for searches. For example,
this is the first result when searching for "Canadian"...
For anybody who cares, here's the error:
DROP command denied to user 'smf'@'192.168.2.11' for table 'smf_tmp_log_search_topics'
File: /web/x86/web/forum/Sources/Search.php
Line: 1006
Why the hell does SMF need "drop" access in the database? That's just asking for a "drop table *" if somebody finds sql injection...