I have just installed ZoneAlarm Free Antivirus + Firewall 2013. After that I have installed Metatrader 5, a well-known application for trading online on the Forex market (http://www.metaquotes.net/en/metatrader5). This application comes in two versions, 32 and 64 bit, an by default on a 64 bit windows system the first one is installed, as in my case. After installing it, when I tried to launch it I got the following error message: The procedure entry point could not be located in the dynamic link library user32.dll.
Since in another pc without ZoneAlarm the same application was working without problems, I immediately imagined that the problem was related to it, and so I experimented a while with settings: disabling firewall had no effect, and also quitting completely ZoneAlarm. Only after I completely uninstalled ZoneAlarm I could make Metatrader 5 to work again.
I did then another experiment: following some suggestions I found on the web for a similar problem, I installed the 32-bit version of Metatrader 5, and in this case the application starts without problems even with ZoneAlarm installed and running.
I already reported this problem to Metatrader 5 developer, but I think that also ZoneAlarm developers should be concerned about this issue sine Metatrader 5 is quite widespread among Forex traders.