[Solved] Using this forum (and others) in Firefox

Sometimes when I'm in the middle of reading Cakewalk or KVR forums, with several tabs open, Firefox turns white for a few seconds. When it comes back, sometimes it can't restore the page I was looking at. This has been going on for a couple of weeks -- before and after upgrading to Firefox Quantum.
 
Event Viewer System log says, "Display driver amdkmdap stopped responding and has successfully recovered."
 
I googled that message, and one of the sites said that the cause is probably the power supply. My PC is six years old, so maybe so. But when I use the forums in Edge or Chrome, I never see the problem.
 
I'm running Windows 10 with 16GB of memory and a dedicated video card with current driver.
 
Any suggestions?

Thanks for the advice.
 
It's the ATI Radeon HD 5400 series with 15.201.1151.1008 driver. I checked the update status of the driver by running Update Driver in Device Manager.
 
I've just turned off hardware acceleration in Firefox, so I'll restart and try the forums again.