firefox portable crash without a clue

IE sucks.
Was using Opera since version 3 and was happy with that until I found the vastness of the Firefox extensions. I use different machines in different times of the day. So turned to the Firefox portable. But to my great disappointment it crashes without any trace of anything. Imeant to say that there is no pattern. First I downloaded the portable firefox 3.0.3. Run it, Configured it, installed my desired extensions all of them are recommended ones except Imglikeopera. Sometime it works fine for hour long sometime it crashes even when I am doing nothing. Then tried to work with a fresh copy without any extension or skin installed. But all the same. It also crashed. No pattern of websites, scripts or anything. But the installed copy of Firefox in the same desktops are working just fine.

Where is the problem guys? Can anyone give any clue to overcome this problem?

I am using windows XP SP2 with Intel Pentium 2.4GHz, 256 MB ram.

Thanks