From the Wikipedia article on Gnutella:

"...with DQ [Dynamic Querying] the search stops as soon as the program has acquired enough search results, which vastly reduces the amount of traffic caused by popular searches."

It appears that this design change has made rare files nearly impossible to find because of the thousands of malicious nodes on the network that return bogus results for every search in an attempt to lure the user to install malware or to visit malicious web sites. Limewire stops returning results after a few hundred results have been delivered, even if all of those results are bogus. Something needs to be done to prevent malicious users from making gnutella unusable.