We had similar problems, I think. If it is happening every 15 minutes from bootup you should look for the watchdog packet negotiation/keep alives. Just another lovely Novell "feature to keep only active users mapped to drives". Capture traffic on both sides of the 8600. make sure your server is sending them/ make sure your workstation is not recieving them. If this is the case, there is an option on your netware server to choose routing options: nlsp or ripXX something like that. I forget which we had to change to, but I think that did the trick. Of course this is assuming that the switch is routing IPX. Nortel could not help us, they said they build a test lab and could not replicate it. We build our own test server and after 2 weeks figured it out. I hope this helps and that it is not too late.