accelerometer reads infinity

[hellochar]

we've had a new problem with our accelerometers that have only recently appeared. Using labVIEW:

1) On our first run of the robot, the accelerometers will read infinity for all axes
2) We then stop the code and re-run it. This time, the accelerometers work correctly for a few reads - three to five readings - and then stops altogether. other sensors still read values
3) We then stop the code and re-run it again. This time, accelerometers work fine.

It repeats this pattern over and over again. we haven't changed any accelerometer initialization/reading code for a while, although we did have to re-sodder the PWM wires a few days ago. I would consider this to be the cause of the problem, but how would a hardware/wiring problem create a deterministic loop?