FortiClient GUI won't open after fresh install

[primetimebio]

I've installed FortiClient 5.6.6 on a PC to setup a VPN for a user. The Install goes fine, after the install it runs its updates and scans and then I try to open the GUI to configure the VPN... Either the window doesn't open at all, or if it does its blank and goes unresponsive. I've tried letting the window sit for awhile and maybe it would work, but no such luck. I've tried uninstalling completely (Revo) rebooting, running updates, etc. Then reinstalling to no avail. This is on a Windows 10 Pro machine, I've tried installing older versions of Forticlient in case it was the installer but I haven't had any luck. I was wondering if anyone has encountered this and has a solution or at least a few ideas. EDIT: I've re-imaged the machine in question and it still won't open the GUI, or if it does, it has to load for about 5 minutes in between clicks within the GUI. Its painful and I'm not sure the user would be happy about having to connect to the VPN using that.

[emnoc]

No  but  you mention "Windows 10 Pro"  that's probably the root of the problem;) What older  version did you  try to install ?

[primetimebio]

I tried older FortiClient installs, I only tried 5.6.5 and 5.6.4.

Its working fine on other Windows 10 Pro machines, this one seems an oddity, but I can't figure out what separates this machine from the rest.

[PKS]

I have the same issue but on Windows 7 Enterprise and FortiClient Version 5.6.6.

Version 5.4.2 did work. But this version has problems with transmission bandwith.

So I updated to 5.6.6. First bad thing: it installs all the optional stuff too.

Second bad thing: The GUI doesn't show up...

Is there anyone with a solution?

[gomadosnitro]

Close EMS

Go to c:\Users\xxxxxxx\AppData\Local\Fortinet\EMS\Console\6.4.3.xxxxx

and rename Cache folder to Cache.old

and open EMS again will create new Cache folder, dont know why but something wrong with this EMS version.