It's possible something corrupted the software. You don't need a CD as your software is always available through your online account, which would have been created when you activated, or verified, the installation.
I would uninstall via Control Panel > Programs and Features, reboot if asked to, then run the MCPR cleanup tool, reboot, then install from the online account.
If you have a problem finding your online account, phone Customer Service, it's free. The link is below.
Toronto ▪ Canada
Volunteer Moderator - Consumer Products
I CAN'T HELP PRIVATELY - PLEASE POST IN THE FORUMS
Use Advanced Search To Find Answers
P.S. a hint to speed things up...download the installer file first and save it to your desktop.
I would follow Colleague Ex_Brit's suggestions. Having said this...Was it your Windows ' Action Center ' warning you, or your Web Advisor? Just out of curiosity I am asking...