Hi! to all.
I have installed on my pc Slackware 12.1, and, few days ago, I upgraded the kernel to 2.6.28.7 version in order to obtain some devices (like lan) working better on my pc.
I have compiled the kernel manually with xconfig, and all is good.
Today I recived a Huawei E172 internet key, I tried on Win and it works fine, but when I go on Linux... I didn't understand what is wrong, but it's still not working. I looked on internet, and I found out a lot of sites about how install and work with this hw, but this new kernel seems to do all withouth my help, it recognized the key as a modem and not like a cd-rom, and there is a module option.c in /linux/driver/usb/serial which looks for this kind of hw. But kppp when I tried to use it disappear withouth any message, and wvdial connect to internet, using this options

[Dialer Defaults]
Modem = /dev/ttyUSB0
ISDN = off
Modem Type = Analog
Modem Baud = 460800
Init2 = ATX3
Init3 = AT+COPS?
Init4 = AT+CGDCONT=1,"ip","ibox.tim.it"
Phone = *99#
Dial Attempts = 10
Dial Command = ATM1L3DT
Ask Password = off
Password = tim
Username = tim
Auto Reconnect = on
Abort on Busy = off
Carrier Check = on
Check Def Route = on
Abort on No Dialtone = on
Stupid Mode = on
Idle Seconds = 0
Auto DNS = on

but I can't access on internet with any program.
I don't know where is the problem, if you need something data, ask it to me.

Can you try a stock kernel and see if it works ? Make sure you included the ppp module and maybe a few others.