Hello. I am wondering if someone else had this problem. I am finding that when we use the Citrix Client internally to connect to a host outside of your network, the ISA Server will crash and receive a blue screen. The error that is reported is as follows. STOP: 0x000000D1 (0x0000000D, 0x00000002, 0x00000000,0x0000000D) DRIVER_IRQL_NOT_LESS_OR_EQUAL. I've tried systematically applying all updates and service packs to the O/S, Windows 2000 Server to see if this would correct the problem. It did not. I tried applying Service Pack 1 for ISA Server (it referenced Q293161 in it's hotfixes), but the same occurs. I have also tried using the latest Citrix Client but to no avail. Q293161 references this as well. "The error message might also occur if IP routing (ICMP pass-through) is enabled and a ping (ICMP) packet that is larger that the MTU setting is sent to a remote host." Can I manually change this MTU Setting? Any help would be greatly appreciated. TIA. Chris