I prefer to use separate A-V and firewall applications rather than a suite so as to get the best in each category. For some time I have been using Zone Alarm Pro as my firewall application, with BitDefender, then Norton as my A-V. Recently, NAV and ZAP have started to conflict with each other over downloaded online data. Web pages hang while loading, and email (POP3) and file downloads fail to complete. I've confirmed this by uninstalling ZAP (reverting to the Win7 firewall) and noting that my online problems have vanished.
I put this down to the trend to increasing integration of these functions into suites rather developing them separately. However, in trying to pull just the firewall function into ZAP, it appears you're also including too much A-V functionality so that ZAP is trying to examine file contents at the same time as NAV, causing file access contention resulting in the browser or email client getting corrupted data. While both Symantec and Checkpoint could be faulted, I think that ZAP is out of bounds here. A firewall should concentrate on controlling application access to the network, and leave the inspection of the data to the A-V application.
I haven't bothered to get support from either vendor, since I'm sure the end result will be a recommendation to use that vendor's suite instead. And I'm afraid I put more weight on A-V performance, so i will probably go with the Norton Suite, but in a year or so I'll check to see if the issue has been resolved so I can move back to ZAP.
One last thing, the versions I've used are Norton Anti-Virus 2012 (ie v19) with the latest update, and ZAP 10.2.074. I also upgraded Norton to v20 (what would be 2013), but the conflict became so bad that my system would boot to the desktop, but then freeze so that all I could do would be to use the power button for a hard shutdown.