It's best to focus on one issue at a time ... the Adobe Flash and mouse issues probably are not related.
Flash:
Uninstall Flash, reboot, and install new from Adobe.
Uninstall: http://helpx.adobe.com/flash-player/kb/uninstall-flash-player-mac-os.html
Install: http://get.adobe.com/flashplayer/
If that doesn't fix it, download Chrome from https://www.google.com/chrome . Chrome has an integrated version of Flash, which is a good test to see if Flash is the root issue or not.
Mouse: If what you describe is repeatable, take the mouse into an Apple store and see if it's the problem. If it is, it's under warranty, get a new one.