What is it?
Zone Alarm - zlclient.exe
What does it do?
zlclient.exe is a part of Zone Labs Internet Security. You should not end this process for any reason. This is the firewall I use behind my router as a second level of protection. The most important part of this is having to give permission to applications before they access the internet in any way. routers and the windows firewall have a tendency to allow anything out and only blocking inbound connections.
You'll want to keep an eye on this google search for any known viruses. The normal location of this file is C:Program Filesone LabsoneAlarmzlclient.exe