Well, i have been using mandrake 9.1 for a while now as server but it has not been loosing ip address. It is working ok. I tried the mandrake 10 community edition, it browsed well but what i can not do was to share internet connection with it. In fact, I did not even find where the option for setting it is located. One funnny part of the mandrake 10 is that every little thing has its own environment which makes it a little tedious to work with.
Coming to the freezing of your Dlink switch, did you connect your wireless AP to it. If you did that is what is causing it to freeze. I have two Dlink switches which i use. I notice that each time i connect my wireless base radio to it directly it often freeze, so what i did was to uplink to another Linksys, then connect the wireless AP to it.
another thing to check in the issue of loosing ip is your network card. What is the make? Why I am saying this, is because i have not notice mandrake loosing ip after rebooting before since ever i have been using it.