Consider the following scenario. In Microsoft Office SharePoint Server 2007 you set the value of the Allow items from this list to appear in search results document library setting to No for a specific document library. Then, you perform a full crawl. In this scenario, the items in the document library are still crawled. Therefore, the items still appear in search results when you perform a search.
To resolve this issue, apply the following hotfix packages:
2412259 Description of the Office SharePoint Server 2007 hotfix package (coreserver-x-none.msp): October 26, 2010
2412258 Description of the Windows SharePoint Services 3.0 hotfix package (Sts-x-none.msp): October 26, 2010