Novell Client / NT Performance Issue

We are running the netware client on our Windows NT/2000 workstations. The problem we are having is with performance when accessing files on the NT Server. Files are very slow to open. As a test,I have removed the Netware client from a few machines and the performance problem goes away and file access is lightning fast. When I reinastall either MS Client for Netware or the latest client from Novell the problem comes back. Any ideas on how to correct this problem?