QuarkXPress Server processes requests successfully when launched without subrenderers. But with 1-4 subrenderers, rendering requests are not processed and remain on the left panel of the console window. When this happens, QuarkXPress Server 7.22 and 7.23 memory and processor usage slowly increases and the application eventually freezes. This problem is fixed in 7.23r1

To resolve the issue, install patch build of QXPS 7.23r1, which is certified for Leopard OS.