We have several machines running with the ISI9234HPCIE modem card. On a handful of those machines, none of the modems function after reboot until we use the ISIPortModemReset utility. After some investigation, I believe I have narrowed the problem down to the fact that the MPIO pins 0-3 are low on the Exar UART instead of high after reboot. I can use an Exar testing tool to manually set them high, and the modems return to being functional without having to use the reset utility.

Can anyone suggest a reason that some machines would boot up with those pins low, when most other machines boot up with them high?