3G USB Modem issues

I’ve been seeing that a 3G modem I bought (Huawei E3131B) has been giving me some problems with the BBB.

Firstly, it sometimes picks up the modem and powers it (light on modem flashing), but then somehow loses contact with it, and the modem no longer functions properly and is not picked up.
Second, my Angstrom hangs sometimes when I plug the modem in and out and when I run programs such as ppp which are meant to connect it.

My best guess is that there is something wrong with the USB driver. How would I go about debugging this?

Cornel