"Your computer need to be restarted".....

[Kenshiro]

Hi,

in the last few weeks I had some problems with PT6.1 and G4/double 1.25Mhz.

Sometimes when I'm working with ProTools my mac suddendly freezes, the screen turns grey and appears the dialog "Your computer needs to be restarted, press power button for several second" (something like that).

I'm not doing anything strange (and the problem appears randomly); does anybody have the same problem?
I tried also to reinstall the system but nothing changes.

To be honest the same problems appeared also the first time I installed PT on the new G4 with a fresh OSX (no other applications installed). The G4 is one of the latest that can start from both OS9 and OSX, with 512Mb RAM and only a Pioneer A06 DVD recorder installed beside the Mac ComboDrive).
It appeared a couple of times at the beginning but now it's about once a day...

Any help?