IMX233 Maxi boot misbehaviour

[edinsam]

We have a IMX233 maxi connected to varios external hardware interfaces via the GPIO ports.

The booting behaviour is rather erratic when the interfaces are connected (i.e. via the 40 way IDC plug) As soon as the HW interfaces are disconnected, the cpu boots properly.

My question is: are there any specific conditions required on the I/O pins during bootup? e.g voltage levels etc.

I am asking this because the manual suggests a diode to be placed on the input UART port line, perhaps to avoid some input condition similar to the one we may be experiencing? 

PS: I am aware one of the GPIO lines also doubles as ethernet device reset! (I found the hard way) :-)