I have an application called Timberline installed on Windows 2000 SP4, Citrix XPA FR3 SP4. Around the time I upgraded to Citrix SP4, Win2K Post SP4 patch, and upgraded to the latest version of Timberline I started receiving an error when Timberline is closed. I didn't detect any errors because no one reported the problem for sometime so I kept upgrading and service packing until everything was updated. After a week or two users reported that when closing out of some Timberline screens or closing out of Timberline they would receive an error: "The Instructions at 0x00ba0b60 referenced memory at 0x00ba0b60. The memory could not be read". You click ok on the error message and it does not appear to cause any problems. 1- I investigated and found that the error only occurs in an ICA or RDP session only. From the console on the server it does not error. 2- I've tried regmon and filemon and neither show any problems that I can tell. 3- I've tried almost everything the vendor has suggested, although they seem to have no clue. They have had me try different printers and are now telling me to reinstall TCP/IP. 4- All other applications (Office, IE, Acrobat) are working perfect on the same servers. I don't know if this is being caused by a service pack, hotfix, application update, or corruption has caused this. I have two servers load balanced and they both exhibit the same symptoms so I think corruption is not likely. Any ideas how I can troubleshoot this? It does appear to be terminal services related as it only occurs within ICA or RDP sessions. Thank you! Matthew Shrewsbury, MCSE+Internet MCSE 2000 CCA Server+ Senior Network Administrator