If you get the error in the title at the crawl logs of the MOSS 2007 farm and googled some, you'll see some solutions like restarting the search services on the farm, detaching the search database of the shared services providers, and things like that. Before trying these solutions, just be sure about this: Do you have "I" ( "aye", the upper case "i" ) character in the URL of the error generating site? If your answer is "Yes", go ahead and change the "I" character to "i" ( the lower-case "I" ) and re-crawl the content source, your problem may have been solved 
kurtlubakla