Add another one to the freezing category!

Running liveusb on LinuxCertified laptop; dual T4300 (2.1 GHz); 2 Gb ram; Intel G45 chipset, 1280 x 800 screen with LinuxMint 12 32bit.
First run-through, like the others, using FF, Banshee in background (accessing music from laptop's hdd); had changed desktop wallpaper to photo on hdd; I had opened and closed several apps, installed wine and e-Sword (a windows-based Bible program) as a test and then began searching with FF when browser lost focus, the mouse would move, but nothing was clickable. Volume control, screen brightness controls also locked. No other key combination worked except CTRL-ALT-Backspace, and then had to hard reboot using the power button. I put it all down to running out of space on my 2Gb usb.

Second run-through, had used FF, and Banshee running again (with same music chosen from same hdd source), closed FF, then opened VLC. Used VLC to view several (three) vids from the laptop hdd, but on trying to open the fourth, the same locked condition as noted above...and same escape using power button.

This could be a timing issue, as it seemed to me to be similar time frame in both instances 10-15 minutes or so.

On the GOOD side, in my use of the system, it seemed faster than 11 (which is my current sole OS on this machine) it was very snappy in accessing files, apps and configuration. 
I have a test laptop (Lenovo T60, dual booting XP with openSUSE 12.1 Gnome). I will install Mint12, replacing the openSUSE to test an installed Mint12 system. I had none of the lockups in using openSUSE, using both FF, and then chromium while using Rhythmbox is the media app (already installed). I did similar usage tests, as above, including installing wine, e-Sword. But I did have to spend time with openSUSE getting codecs, installing peripherals which I did not need to do with Mint. 

Hope this helps!  I will report back on the T60 test.

-- EDIT --
Well, installed Mint 12 on the T60 it took 30 minutes for it to freeze, right as an update finished! Banshee is still playing an audio (i had forgotten that little bit, this was true in the other freezing instances, too). The FF window lost focus as the update finished. The mouse cursor moves (trackpad is not working [worked while live], which is why i did update, thinking it would get it working after the install.) But since Lenovo's have the Trackpoint, I was still able to move around. But clicking does not get a response, in notification area in top panel, bring up the menu or the desktop windows in the bottom panel. Cannot close minimize or move FF window. Banshee continues to play audio files one after another. I can still change volume and brightness with the T60, however.
I am puzzled! and glad I didn't install on my production system!

-- Second EDIT --
The update DID fix the T60 trackpad issue, I have also installed chromium and removed FF as a test.  

-- Third EDIT -- and SOLVED?
Ok, I have been over an hour with Mint 12 installed on a T60, with no freezing, have six desktop windows open, Banshee playing, youtube video playing in Chromium, 3 powerpoints open and play one every so often, downloading audacity with synaptic, while downloading and installing a windows program through wine.  No freezing... don't think it is Banshee's fault ... I think we can place this at Firefox's feet, or at least it may have a problem with Banshee.

-- Fourth EDIT --
Froze today. Had chrome open, Banshee playing, Gimp open, terminal open and working in it, when the freeze happened. Mouse moves, but no clicks register on anything. hard reboot. I was reading a bug report on this combination causing this freeze, so I had to try it. [b]It is NOT Firefox's fault... sorry.[/b]