If I have Microsoft Word open, the computer will eventually hangup when Firefox is open at the same time. It seems to me there is some sort of memory address conflict. Two different programs accessing the same memory locations creates a conflict between those two programs. If I want to change the brightness, I will open the Graphics Properties, and will select Intel HD Graphics Control Panel. Firefox also interferes with that program. The web pages are too dark in comparison to the brightness of offline software applications. I wish Firefox would turn up the brightness. Now the other problem has to do with Adobe Reader. Firefox also interferes with that program. In computer programming classes they told us about assigning memory on the Stack and on the Heap. And to be careful with Pointers. Make sure to not address memory at certain locations, and to give back the memory after the routine has finished. What I have been experiencing with Firefox ever since the 64 bit version was introduced, is a very serious problem with memory leaks.
I'm experiencing the same on Ubuntu lately. Firefox completely saturates every byte of usable ram until the system starts swapping and then stalls.
Please share some details like the version of Firefox (Help->About menu). And use task manager to view actual Ram usage to share some numbers. This will help Mozilla devs to understand what code branch you're using and at what Ram levels or time after opening you start seeing a lock-up.
(Help->About menu)Is Not Available. Ever since 64-bit versions were introduced, these versions of Firefox interfere with other programs such as Microsoft Word, Adobe Reader, Intel HD Graphics Control Panel, etc.
Sorry assumed you actually use the menu on Firefox. But realise many people don't.
Here's a link with step by step pictures: https://support.mozilla.org/en-US/kb/find-what-version-firefox-you-are-using