Errore di ricerca nelle FAQ

Ciao,
quando cerco qualche termine nelle FAQ mi arriva una mail con il seguente rrore:

Invalid SQL:
SELECT faqname, faqparent, phrase.text AS title
FROM vb_faq AS faq
INNER JOIN vb_phrase AS phrase ON(phrase.phrasetypeid = 7000 AND phrase.varname = faq.faqname)
WHERE phrase.languageid IN(-1, 0, 2)
AND (
faqparent IN('vb_email_member', 'vb_memberlist_how')
OR
faqname IN('vb_email_member', 'vb_memberlist_how')
)

mysql error: Illegal mix of collations (latin1_bin,IMPLICIT) and (latin1_swedish_ci,IMPLICIT) for operation '='

mysql error number: 1267

Qualche idea del perchè?

Grazie.