Getting hammered with pop up adds here

Daves69 said
Does it reboot when it goes black or does it return to the screen you were on?
Check for air flow. Vacuum the dust out of the vents. Shut down and re-seat all cables.
Should be able to make you own recovery disc(s) or purchase "IF" still available.

On this machine I'm using IE 11 with no issues on this site. Win7
MS Security Essentials
Malwarebytes Free

You might try Spybot Search & Destroy if your "confuser" has the resources.

For no apparent reason the screen goes black and then flashes back on again.

Probably a corrupted video driver.
Sometimes just removing the video from device manager and letting the computer reinstall it works, and sometimes downloading a fresh driver is required.

I run across this all the time on computers I clean up.