If you are using FIPS, your ClickOnce applications might not work. I ran into this bug running BookSmarts, an application I wrote. Turned FIPS on and started receiving errors.
The issue is that enabling FIPS makes the mechanism that verifies the validity of ClickOnce applications fail every time.
The article, a very long one, can be found here: https://support.microsoft.com/en-us/kb/811833
Just keep this in mind if you are trying to support someone who is the odd ball out.
Note: Enabling/Disabling FIPS in Windows is done through the registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\FipsAlgorithmPolicy\Enabled (DWORD)
1 is on, 0 is off
When changing this setting, it’s necessary to reboot the computer.