Not fixed for me. 
Took a fresh 3.8 install on VirtualBox and let it update today.
Actually, it did run FF 85 ONCE, and OS asked to reboot so I let it. Now FF dead.
Originally the problem was it did nothing, now I get the spinning cursor only it stops spinning.
Can't access the menu, so I guess it's locked up.
On my netbook, I'm going to continue using the fresh install, only update the Firefox.
EDIT: Gave the VM machine 2 CPUs and FF ran. Can't do that with the netbook or P4 box....
Actually, when you give a VM a second core you must enable "I/O APIC" and that's what seemed to do it.
(Still not gonna mess with the netbook)
Took a fresh 3.8 install on VirtualBox and let it update today.
Actually, it did run FF 85 ONCE, and OS asked to reboot so I let it. Now FF dead.
Originally the problem was it did nothing, now I get the spinning cursor only it stops spinning.
Can't access the menu, so I guess it's locked up.
On my netbook, I'm going to continue using the fresh install, only update the Firefox.
EDIT: Gave the VM machine 2 CPUs and FF ran. Can't do that with the netbook or P4 box....
Actually, when you give a VM a second core you must enable "I/O APIC" and that's what seemed to do it.
(Still not gonna mess with the netbook)