I have the exact same problem regarding port settings disappearing.
Been running 132NA for a little over a month or so with no problems, but when I needed to open some ports due to SSL servers on my net I quickly found that any new changes would be discarded, and I do mean ANY new changes at all I tried to make, not just port forwarding, virtual server and application rules, but also remote management settings.
I have tried about everything I could think of and a googled a lot for any solution, but none has shown up..
Finally yesterday I decided to try 132NA beta 09 and I typed in the ports needed. Woho, today the changes are still in place, but since I needed to add some extra rules I found that the router once again drops ANY changes I make.. at least it remembers the first set of settings I set up, but I can't upgrade firmware everytime I need to make a change...
I'm NOT normally into beta anything on my router or other critical devices, so the beta 09 was a huge step to take and I only did it reluctantly.
RMA form on dlink keeps erroring out for me, so cant contact support, sadly.
So, for now I'm stuck without port 443 open, which means I can't access HTTPS servers, which is very bad for business...