Allegro 2961 uptdate

I have the PWM drive up and running and am doing some testing with
a dyno, torque and speed are very good. I did run into a problem
though and wondered if anybody had
any ideas on how to handle it.
Everything works very well when I turn power on first to the 5 volt
logic power supply wich turns on the 5804 that does the stepping.
This at the same time brings all 4 PWM chips high(High = off) on the
input pins (these are then tied to the 5804).
The problem is when I turn on the 40 volt supply first then turn on
the 5 volt it blows out some of the PWM chips. The 2961's have an
enable pin that I have tied high to the 5 volt supply,(High on these
enables the chip).
Does anybody have any ideas on how to handle this, other than to be
sure I always turn the 5v supply on first (a recipe for disaster)
One idea I had was to use a 5v zener off of the 40volt to keep the
inputs of the 2961's high when the 5v supply is off line.
Lonnie