Error Installing Xwiki

Hi All, I'm a new user in xwiki and i recently installed it. One error appeared in the "news" in the main page. The error is: Error number 4001 in 4: Error while parsing velocity page Main.WebHome Wrapped Exception: Invocation of method 'searchDocuments' in class com.xpn.xwiki.api.XWiki threw exception class com.xpn.xwiki.XWikiException : Error number 3223 in 3: Exception while searching documents with sql , BaseObject as obj where obj.name=doc.fullName and obj.className='XWiki.ArticleClass' and obj.name<>'XWiki.ArticleClassTemplate' order by doc.creationDate desc Wrapped Exception: could not execute query Probabily it isn't only in the news page but in another place too. Does anyone knows how to correct it? Thank's in advance Ivan Koga