Whatever happened to the customer is always right? Take heed - if someone says your service is broken (even if it's not), you may just want to listen, not point fingers, and take the heat. Otherwise, you'll risk some negative feelings - especially if it happens on a support forum.
An interesting thread has been occuring on the Yahoo! Site Explorer Suggestion Board now for one month about Yahoo! not indexing a webmaster's pages and not counting links properly. Apparently, only one page of the webmaster's site was indexed (the home page), when several thousand pages had been indexed before, and, the number of backlinks dropped from several hundred to zero. Instead of trying to figure out the problem on his own, a Yahoo Site Explorer employee suggested that the site may be in violation of content guidelines and suggested that the webmaster contact Yahoo Search Customer Care to figure out if he was in violation of said guidelines. I don't know about you, but if someone told me I was in violation of some guidelines and I wasn't, I would not be pleased.
Fortunately, another moderater joined the conversation and said the Site Explorer statistics page "is not reliable at present and is showing zero counts for some sites that are crawled and indexed successfuly." Clearly the latter response was not easy to admit, but it did/does solve the problem of a customer inquiring as to what is actually happening.
I tested Site Explorer this morning and found no errors. If Site Explorer is having issues providing accurate information about your website, visit http://search.yahoo.com and search on 'site:mysite.com' to receive a result page showing your correct page counts.