right click menu keeps popping up

AS of late, within 10-15 inutes after re-boting my iMac (intel) will suddenly open the right click context menu anytime/anywhere on the screen that I click.When this starts I can no longer type into any text field wether online or locally. Usually at about the same time when I fingertip scroll using the same magic mouse the ENTIRE desktop enlarges or resumes normal size.

I have been using the magic mouse for a looong time and never had any issues untill last week.

I have even disabled my right click capacity in the Preferences Mouse menu. Even tried switching back to my USB mac mouse. I have put in fresh batteries all with no change.

Upon re-booting the computer acts normal for some time.

I have gone back in my time machine w/o any change or effect.

I have unplugged all USB connections except the keyboard, re-booted and it still happens after a bit of usage.

Totally Perplexed by this.

Truly appreciate the help

Regards

Russ