Current Liferea versions up to 1.8.11 do provide a link to feedvalidator.org upon feed parsing errors. The idea is for end-users to be able to verify correctness/well-formedness of the feed formats as provided by different websites/blogs. While Sam Ruby's feedvalidator.org (from my point of view) did always provide a correct analysis of the feeds it was recently reported to deliver malware. It might be that the malware detection by Google is bogus (see current Google report showing 5 malicious pages on 29.12.2012), but to eliminate this error class altogether I decided to drop the link. Until you upgrade to a newer version of Liferea: Please do not use the feed validation link!