Wow!!! I never have seen something like that before...
Are your VGA drivers up to date? Latest drivers tend to have less problems with hardware acceleration.
Depending if you feel that things go faster or not, you can always disable hardware acceleration and rely on your CPU entirely, that fixes many problems...
Note:
Maybe Hardware Acceleration only works on Intel machines.
I have discovered that some software expects you to be using Intel hardware (e.g. Android Studio).
My desktop machines use AMD hardware.
In the case of Firefox, they are supposed to be working with a lot of setups, this includes nVidia, ATI or even Intel HD graphics.
The problem is that, they insist on relying on the DirectX API to use hardware acceleration, which has been proven to be faulty, buggy and in general, quite unstable. OpenGL by the other hand, is a much better option (I've tested it when Firefox was in works of Hardware Accel, it was quite good) and it's way faster than DirectX when handled right.
Now, is this fault of DirectX? Nope, Why? Because Chrome and IE can use hardware acceleration in a really neat way, and neither of them crash or exhibit bugs... The problem is that Mozilla team seem clueless using this API (remember Firefox garbled text problems when the platform update for IE10-11 came out? Neither IE nor Chrome had this problems...)
Not being able to fully handle an API can lead to nasty bugs... OpenGL seems like abetter solution for me and Firefox... but let's see what Mozilla thinks about it...
