I had tried "kdesu dolphin" earlier in Mint 13 but it didn't work there.
Anyway, this Huawei E173 usb modem exhibits the same behaviour in my fresh install of Sabayon 11 KDE 64bit.
Decided to try Mint 14.1 Cinnamon and see how it would behave there. Same deal, fails to connect.
If I go back to Mint 13 without powercycling the modem it will do the same thing there until it gets unplugged and plugged back in. Now i'm convinced it's being incorrectly initialised due to some change in usb-modeswitch. I've been denying updates in Mint 13 since late January when this problem appeared so that one still works.
After noticing some additional references to E173 in the latest 40-usb_modeswitch.rules file I thought I'd try swapping in the old one. It didn't help.
I'll start a thread at ModeSwitchForum. This is not a Sabayon problem.