It turned out to be something very simple, but which wasn't obvious to check to begin with. There was another computer (a Windows machine) that was supposed to have been taken out of service a long time ago, but someone has recently put it back on the network. Because it was supposed to have been no longer used, it's IP address was re-allocated (a year and a half ago!) to the machine that I have been agonizing over all week. On someone's suggestion, I decided to put the problem PC on a different subnet, because we thought it might be something amiss with the new networking hardware that was installed a month or so ago, and suddenly the problem went away. Some more investigation, and we discovered that the IP address was still being used, and, thus, stumbled across the actual problem. Thank you to all who responded! It's always the simplest things, in the last place you look... --- Mike VanHorn Senior Computer Systems Administrator College of Engineering and Computer Science Wright State University 265 Russ Engineering Center 937-775-5157 michael.vanhorn at wright.edu http://www.cecs.wright.edu/~mvanhorn/