Over the past couple of months, when using the latest Firefox, launching the Flash Play window usually resulted in a white or black flash screen, often with audio only, but sometimes a complete crash of the browser.
FIX: Before launching, I right-clicked on the left flash panel and chose Settings, then UNchecked the Enable Hardware Acceleration box. Haven't had a crash since, and it's been a week or more. Hope it stays that way!
:)