Installing the Comodo firewall on my Acer Laptop 9410 running Windows XP Home, I noticed the option to turn on Data Execution Protection. I switched to this firewall because when I downloaded the latest version of Zone Alarm Security Suite and ran the virus scan my computer could not be rebooted properly. Several Windows programs (including Windows Explorer) would not run and blocked other programs from loading. I had to completely reload my operating system, programs, and files. I had to do it a second time after updating the Zone Alarm program and scanning for viruses again. In both cases no viruses were found but my computer would not boot properly. Naturally I was reluctand to turn on Data Execution Protection. Do I need it? Will it damage my software again? I do not understand what it does or how it works.
You said you noticed the option to turn on Data Execution Protection, so I am assuming that you have installed a version of CFP. Later in your same post, you mentioned updating Zone Alarm.
Do you have both firewalls? Comodo and Zone Alarm?
If so, you’re asking for trouble. It’s like trying to have two people drive the one car at the same time.
If you decide you want to use CFP, please do a search on this forum for “ZA” or “Zone Alarm”. This is a recent post with a link to a ZA removal tools. Zone Alarm does not completely remove it self when you uninstall it, and subsequent installations of other firewalls (not just Comodo) wil cause you grief until ALL vestiges of ZA have been exorcised from your system.
Ewen 
Zone Alarm was completely removed. Now I have the Comodo Firewall with Data Execution Protection activated. So far no crashes. Some others problems:
1- Window Security Alert does not recognize Comodo Firewall even though the manual say it will. Security Alert stays lit and says I need to activat a firewal.
2- Every time I open a program the Comodo wants permission to allow it. I check remember setting and allow. I contines to question over & over. Any clues as to what is happening? ???
Hi jerrypinsky:
** FAQs/Threads - Read Me First ** → Great place to find answers
1- https://forums.comodo.com/index.php/topic,2479.msg19751.html#msg19751