We are working on issues like this right now.
We have had one case that got no com port function whatsoever regardless of what we did in order to debug and fix it - until the person in question reinstalled Windows. We still don't know why he had to do that, it just looked like Windows failed using the com port even though it gladly installed it.
I am not saying reinstalling Windows is for you too, just mention it so that you know we are trying our best here. Another problem is that we don't see these problems ourselves, and therefore debugging is extremely difficult.
There will be a new version of the com port driver which will log messages to Windows' system log. It will make pinpointing what is wrong much easier.