Hi Folks I found out the main issue with respect to the application"WFSHELL.exe and other server application's Memory couldn't be read error" in Citrix MF SP4 (Windows 2000 SP4) We need to update the 1. Update the Windows2000-KB891861-v2-x86-ENU (Update Roll-Up version 2) 2. Update Citrix Hot Fix :- Update Roll-up 1 for MS SP4: --- XE104W2KR01 3. Citrix Hot Fix :- Post HRP 01 Hot fix 1 -- XE104R01W2K010 4. Citrix Hot Fix :- Post HRP 01 Hot fix 2 -- XE104R01W2K012 But one of my applications is having a problem because of Microsoft DEP. For this we suspect the mfaphook.dll which comes along with MF SP4 is conflicting. Anybody can get me the "mfaphook.dll" from any one of ur servers where MF XP FR3 SP4 installed? Please help Regards ____________________________ nagarajan haridas ,CCA Symphony Offshore Operations- EPM NA SLK Software Services: Bangalore: India