Pardon me if I'm wrong, but wouldn't using the bookmarks in your pc's browser (I.E., Firefox, etc.) solve this problem, rather than using 3rd party search-engine bookmarks?
The advantage of yahoo/google bookmarks is that they follow you when you make changes on all your computers.
That being said, the fact that it happens when people do a search on yahoo/google that leads them to this site is a pretty serious problem. Instead of coming here they find themselves downloading a virus. They back out and never try to come to this site again.
I know this site, so despite this problem I come back. New people will not do so. Something is corrupting yahoo and google search results and bookmarks for this site. Which makes me think there has been a subtle hack here. Something that is not affecting most people, just a few. When these sites send a user here, there must be something different than just the URL, it is probably something that indicates a referral. This is what is triggering this issue. This site must treat the referral different (could just be a statistic) and this is what is what has been corrupted.
I hate to say it but there is definitely a corruption here. It is not mainstream, and it is not affecting regular users that use browser bookmarks to get here. It is affecting those that come in via search and via third party bookmarks. Perhaps a gift left by the last hacker that broke in here.
