I think you were indeed affected by a rogue variant of Fakealert, which shows up lots of threats and then prompts the user to buy the product.
some of the fakealert variants check for exisiting AV softwares and do overwrite/disable them.
Since your McAfee subscription ended in December, i suppose the rogue application has done a similar thing on your system. i feel your system is not fully cleaned up yet and there might be quite a few files or registry entries present which is not allowing Security Center to run and may be that is the reason you are getting an error "Application not found".
Please contact technical support regarding this and also try booting your system in Safe mode and see if you can submit any suspicious files. Contact details below:
Single User/Retail Customers:
For Home Users, customers can call to 1-866-622-3911 to reach Technical Support.