With Firefox 12 installed, what version of the graphics driver do you have installed? Update your video card driver, then test again. Upgrade your graphics drivers to use hardware acceleration and WebGL

If that doesn't work, disable hardware acceleration. Turning off hardware acceleration. Firefox uses your graphics card to speed up rendering of some parts of some webpages, and if your graphics driver is out of date or conflicting, this could be causing it.

umm first off...how can edit my TOPIC?...my poor typing make me look silly .LOL

video driver downloaded from nvidia site (oem as always with new hardware)

296.10-desktop-winxp-64bit-english-whql.exe 

nic downloaded from realtek.com yesterday. seemed newer version than motherboard driver pack PCIE_Install_5794_03162012

current motherboard please note problem existed before installing this board 2 days ago. Biostar.A770E3.AM3 drivers downloaded from here: http://206.108.48.60/app/en/mb/introduction.php?S_ID=450

yes turning off hardware acceleration allows the browser to work well however my game(s) will require it.in addition there is another symptom in that creating new empty profile allows firefox to function well BEFORE switching to already running game stored in BACKGROUND where as switching to my loaded profile firefox has alot of hiccup and freeze in this PRE-GAME switch.

apologies for omiting this detail originally but the WINDOWS event manager records this error every time firefox locks up

"Windows cannot log you on because your profile cannot be loaded. Check that you are connected to the network, or that your network is functioning correctly. If this problem persists, contact your network administrator. "

and sometimes :

"Hanging application firefox.exe, version 12.0.0.4493, hang module hungapp, version 0.0.0.0, hang address 0x00000000."

i have a few of those from different versions i tried.