Print blow-ups

Our network is primarily NT 4.0 (a few 2000)servers with Win 98 workstations. We have recently started having random blow-ups when users go to print. There have also been many system lock-ups. We have been unable to determine a change to the network that may be causing the problem. We thought it seemed like a DNS server problem so we investigated and found that there was a large patch. This was applied yesterday (12/10/01) in hopes that our problems would go away. They haven't! Any ideasto look for??