PTLE 6.7 Crashing inconsistently,Is MBox to blame?

[js54]

I got an iMac G5 with PT LE 6.7 and an Mbox been working fine for months, not a single crash, but in the last week, PT has started to crash at random!!!

I reinstalled as per the instructions at the top of the forum, did all steps except create a new admin account(that seems like an awkward solution for a "preferences" problem).

I went to my local Mac store and ran disk warrior and had them look at it. They concluded that its probably the USB ports/MBox.

After that it crashed last night after being open for a minute. I then reconnected the USB cable to the iMac and MBox, relaunched PT and was able to work for an hour with 28 audio tracks going with no crashes!!!!

WTF????

I would think that if this was a preferences issue, PT would crash soon after launch (I had this problem once).
Could the USB ports/MBox be the issue??? Or might I have some other PT software issue?

Need help because I cant id a discrete cause.

Is it OK and normal for PT to crash for no reason?

Thanks!