Have had exactly the same problem. My free version was changed to a Pro version after a System Restore and I then got a red pop up that the Pro version had expired.
Stupidly I paid to update the Pro version, but am still getting alternate message: one saying I have 365 days coverage and the next message saying the Pro version has expired.
Also getting messages that my anti-virus system is not updated.
It takes several attempts, using systems Restore to restart my computer after a re-start, needed to complete the installation pf Pro.
In the last couple of days everything seems to have become screwed up!
Also getting constant messages about vital windows updates, but cannot restart the computer after downloading these.
This is a cry for help from a REAL novice