Imagine the situation that you are on Network Solutions website and you search for "ThisDomainSurelyDoesntExist.com" and find that it is available. You decide to purchase this domain from another registrar, and find that it is taken. You are confused, because you just looked up that domain and now it is taken. In this case, Network Solutions has registered the domain, taking advantage of the 5-day "domain tasting" grace period, where a domain can be registered and then returned back within 5 days.
Network Solutions is in the spotlight for doing "front running" which was suspected, but never before proved.
Some articles that go further in depth on this scandalous issue:
Domain Registrar Network Solutions Front Running On Whois Searches
Nominet Position Paper on Front Running
NSI Registers Every Domain Checked
Network Solutions Responds to Front Running Accusations
Reading the comments by the readers to the Network Solutions statement, you can get a feel that no one is buying their answer (or their high priced domains ;) )
Network Solutions is not alone in these gray-area practices, they just happen to have gotten caught.
Domainers are all watching to see what ICANN will do. The odds are on ICANN doing a hand slap and nothing more.
Fight the bit-slapping!
I went to do a lookup for: StealThisDomainFromMe.com at Network Solutions, and the domain was available to register with the result: Domain Status: Never Registered Before
Then i did a lookup at: domaintools and look what it says not more than 1 minute later:
ICANN Registrar: NETWORK SOLUTIONS, LLC.
Checking on GoDaddy, i can't register this domain name because its "taken".