CAUSE :
This is a default behavior seen in SharePoint that anonymous users do not get search results. Security trimming prevents anonymous users from seeing items in search by default.
RESOLUTION in MOSS 2007:
Enable “Always index all ASPX pages on this site” on the site collection.
Perform the following steps:
• Open the SharePoint Site
• Click on Site Actions, Site Settings and Modify Site Settings
• Click on Search Visibility
• Select the option that says “Always index all ASPX pages on this site”
• Perform a full crawl again
• Log into the site anonymously and perform search and you should get search results now
Resolution in Moss 2010:
Enable “Always index all ASPX pages on this site” on the site collection.
Perform the following steps:
• Open the SharePoint Site
• Click on Site Actions, Site Settings
• Click on Search and offline availability
• Select the option that says “Always index all ASPX pages on this site”
• Perform a full crawl again
• Log into the site anonymously and perform search and you should get search results now