flashing screen

Recently (past week), once in awhile screen flashes while on internet. Could this be malware, adware, or virus related? And if so, how do I detect what it is?

May or may not be related to above issue.

Also, my default search engine is Google - after I type in question and press return, Google directs me to a site. But when I click on web site it will go directly to Bing with more search topics. if I press the back arrow the screen goes empty. What could cause this ?