thunderbird and Gmail imap server connection timeout

Hello. I am evaluating Smart Security 5 to possibly protect our 4 laptops, after dumping McAfee due to how they run their business.

I am running Thunderbird V17.0.2 and I am getting "connection to server" timeouts when accessing my Gmail IMAP server when checking email or switching folders.

I have looked on this forum and read about the various Tbird issues. I tried to uncheck "Integrate into Mozilla Thunderbird" under Email Client Integration, but that didn't help. I then tried checking Thunderbird on the "Apps excluded from protocol filtering" - this "fixes" the timeouts. But, does this mean that any emails downloaded from Gmail aren't getting scanned? That's not really a fix.

I admit I am getting very confused at the many options under "Web and email" setup. If there is something else to tweak, I am not getting it. Any help, pointers, RTFMs appreciated.

Thanks for your time.