Have been using Sniffer for about 18 months on my WinXP laptop. Have always downloaded the latest Service Packs when they became available. Saw the new SP4 (30Mar 2004) and downloaded and installed per instructions; being careful to use new Sniffer Protocol driver for my Xircom (Sniffer) NIC. My Sniffer program stops every 15 minutes with a dialog box stating 'Sniffer has encountered an error and needs to shut down.' Can open the dialog box and see this: "AppName:sniffer.exe AppVer:4.70.522.0 ModVer:5.1.2600.1240 Offset:003b2c". This has happened five times this morning. This has happened only since installing SP4. Have removed SP4 and re-installed SP3 and have run Sniffer past the fifteen minutes benchmark failure point. Has anyone else had this same problem?