What's the possible cause of freezing, is it Firefox 7 or Sandboxie?

I was wondering...coz after about 3-4 hrs of surfing the net and while downloading 2 files w/ Internet Download Manager my Firefox 7 browser freezes and I couldn't even close it, even using task manager was useless, it didn't respond. My Firefox was in a Sandboxie mode. I have no other way but to re-set/re-boot/restart my pc.

This thing didn't happens using older Firefox browsers.

Did this problem also occured with you? Couldn't figure it out if this was caused by browser under Sandboxie, or Firefox 7 has some bugs, or some of my addons are causing this problem.

 

Did you try right-clicking on the Sandboxie Control tray icon and selecting Terminate All Programs in order to terminate the frozen browser session?

If this works, it would point to Firefox being the culprit rather than Sandboxie; not to mention the fact that you wouldn't then need to resort to rebooting the PC.