Just a quick reminder to myself, FortiClient SSL VPN can drop the dialing process if the “Mcafee security scan plus” is installed on the PC.
Check in “add/remove programs” if you see the “Mcafee security scan plus”, uninstall it and try to connect again.
A lot of security software like anti-viruses and personal firewalls can interfere with the dialing process of the SSL VPN, try to disable them if the problems persists.
Update:
Microsoft Security Essentials is blocking the dialing process too.
Update 2:
Try to disable IPV6 from network setting.