I'm using a PC with Win 7 ultimate and when trying to connect to a Network Connect page, after Host Checker is executed, then that error happens.
What I've done so far
Clean cache, cookies, etc.
Clean uninstall and reinstall it
Deactivate Comodo FW and activate Win 7 FW
Try to restart service
You can find attached the Network Connect logs
I have a laptop with same OS and firewall (Comodo), and on the same network has no issues.