If you activate the Power Suite with your purchased serial number and get the message "Unknown error. Please contact simplitec customer service."
This error can occur when the TLS protocols for the Internet are not enabled. This is due to Microsoft removing SSL support along with Windows XP.
To enable the TLS protocols:
Go to Control Panel > Network and Internet > Internet Options.
Click the Advanced tab and scroll down the list to Security until you find settings TLS 1.0, TLS 1.1 and TLS 1.2.
Make sure all these settings are enabled and click Apply and OK.