Well, seems like I’m not the only one who has seen this on 3.1.2.  The fix was a pain. I had to uninstall MiWi and do a deep reboot a few times.  MiWi FAIL!.  The problem is that MiWi on 3.1.2 somehow messes up with the network carrior settings, not fully sure what it does, but after I installed and used MiWi, which worked fine btw, I had to turn off and on my radios if I wanted to use them, this means edge, 3G and WIFI.  The fix is to do a  number of reboots, and if that does not work for you, try resetting the network carrier setting.

I ended up reinstalling PDANet and had to reinstall the SBSetting switch for PDANet as well.  Has anyone else experienced this?  Let us know, but for now, if you are 3.1.2 3g or 3gs, you may want to keep away from MiWi and stick with PDANet.  Sure you cannot connect you ipad because the ipad cannot support ad-hoc connections, but else its been a great tool that I have used for years and sits as No. 3 in my top 10 list of jailbreak apps.