Before I have installed Comodo Firewall, I have set Windows XP’s Data Execution prevention (DEP) to ‘on’ for all programs, and DEP worked fine without any problems. After a while, I set it to Windows programs and services only.
When I installed Comodo Firewall, it gave me the option to turn on DEP for all programs. I chose to turn DEP on for all programs again, and after that, some of my programs (Counter Strike: Condition Zero, Riva FLV Player, Portable Opera and a few other programs) don’t run anymore. Opening them gives no prompt or error message - they just don’t run. I have tried setting DEP for Windows Programs and services only and they work fine if this is the setting I choose.
I tried to test DEP again and I turned on DEP for all programs and then included Condition Zero’s executable in the DEP exclusion list and it works without any problems. My processor (Intel Celeron M) supports hardware-based DEP protection.
My concern is that I won’t know if DEP is the cause of a program not running as Windows XP doesn’t give any error messages/warnings if it blocks a program from running. I am wondering if Comodo Firewall could have changed a setting somewhere. In other Windows XP sytems, I have observed that Windows XP does indeed show an alert if DEP has closed a program.