As far as I know neither NOK nor INFN suffer from product quality problems, I would think that publications like LightReading.com would have had some coverage if this was the case.

I believe the problem is a combination of pricing presures, customers being acquired, a still persistent CapEx issue (i.e. customer holding back on CapEx), and the fact that management of both companies failed to set proper expectations nor executed well over the past two to three years.