It seems to be a problem with a cache file filling up. As an experiment, I unlisted the directories that I was sharing and the lockups disappeared. The program that handles search requests (afiledb) is a resource hog, so the more files in your shared directory the more unresponsive Gnotella becomes. This should be fixed in the next revision, as they are working on the resource hogging problem. Until then, keep the # of files in your directories small, or try unchecking seach full path of file so it only scans the end directory where the files reside