Have you ever researched an Internet domain, waited a bit and then, when you go to buy it, it’s gone? You may have been a victim of whois hijacking.
Through a mechanism not yet well understood, some domain squatters are able to get information on domain lookups, which are performed using a protocol named “whois”. They use it to quickly – and automatically – register the domain. This practice is usually combined with domain tasting, so the domains may be available again before too long.
In the meantime, the squatters put up an ad page on the site. If it gets hits, they keep the site. They also usually put up a link through which you can buy the site from them (at a vastly higher price than if you had gotten it first).
What can you do? Until there is a good understanding of how the whois requests are intercepted, all you can do is to move quickly to register domains once you see they are free.