This has been in the news for a little while, it is something a lot of people had wondered when it would happen rather than if. When you search to see if a domain is available using the Network Solutions site, you are locking yourself into buying that domain from them at an uncompetative price or risking loosing the registration to someone else!
What NS are doing is registering every domain searched for taking advantage of the fact a registrar doesn’t have to pay for 3 days for an initial ‘client hold’ registration. If you don’t buy within the 3 days, which can only be done from them at a higher price than most registrars; the domain will be released, but at this stage that domain is out there in the public eye and it may well be picked up by someone else, maybe using NS autoregistration services.
They are expensive and have tried many similar tricks before, I do not recommend them in any way despite the fact they are the oldest and biggest this really means nothing, see your domain is your lifeblood.
I did a few searches on their site including ‘network-solutions-are-shit’ for my own amusement, which if you look up a whois …..

… is now registered with NS and unavailable to buy at a decent price. This cannot be right! After the domain wildcard fiasco and many many other dubious practises that NS have been involved in (just Google em), shouldn’t something be done.
For now all you can do is avoid them like the plague. I recommend Hostgator for registration (through their Registry Rocket) and Domain Tools for searches.