This seems to happen after each build update, and it is usually fixed by the app-cache repair

Get-appxpackage -all *shellexperience* -packagetype bundle |% {add-appxpackage -register -disabledevelopmentmode ($_.installlocation + \appxmetadata\appxbundlemanifest.xml)}

However that isn't working this time.

In event viewer I'm seeing these type of errors appear each time I try to open the start menu

"Activation of app Microsoft.Cortana_8wekyb3d8bbwe!CortanaUI failed with error: The operation was blocked by parental controls. See the Microsoft-Windows-TWinUI/Operational log for additional information."

and

"Unable to start a DCOM Server: CortanaUI as Unavailable/Unavailable. The error: "346" Happened while starting this command:
"C:\Program Files\WindowsApps\Microsoft.Cortana_1.4.3.156_x64__8wekyb3d8bbwe\SearchUI.exe" -ServerName:CortanaUI.AppXwbw90g5vtrwjvhq9gjet3rhd0cy7ctte.mca"

I do use family safety, however the account I am logged on with is a local admin and is a parent account that is not monitored by family safety.

Another example, if I try to launch the Spartan browser, it flashes up briefly then closes. The TwinUI/Operational log give the "blocked by parental controls" error, followed by an Informational entry saying

"Activation of app Microsoft.Windows.Spartan_cw5n1h2txyewy!Microsoft.Spartan.Spartan attempted. Execution state: Attempted activation of the app, 7, The operation completed successfully.."

Any thoughts or suggestions?

You're not alone :( http://answers.microsoft.com/en-us/insider/forum/insider_wintp-insider_desktop/all-modern-apps-blocked-by-parental-control/13781d67-1f7f-4a8e-bdb1-c0bdb022233a?page=1

Thanks, I'll add myself to that thread instead then.