Depending on which USB port I use to connect my HSDPA modem, the network manager will connect to the internet or not. I used to work (i.e. established a internet connection automatically) on all ports, but over time it simply stopped on some ports.

lsusb output in all cases looks like that (Device ID varies depending on USB port):

Bus 001 Device 009: ID 12d1:1003 Huawei Technologies Co., Ltd. E220 HSDPA Modem / E270 HSDPA/HSUPA Modem

Any ideas what could cause this behaviour? What can I do to fix this?

ADDED
One additional information about the modem: if connected via USB it will be available as as harddrive AND as a HSDPA modem (kind of a duality...). In the error case, it will only be shown as a harddrive.

ADDITIONAL INFO AS REQUESTED

MODEM NOT WORKING

Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 002: ID 413c:8000 Dell Computer Corp. BC02 Bluetooth Adapter
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 007: ID 12d1:1003 Huawei Technologies Co., Ltd. E220 HSDPA Modem / E270 HSDPA/HSUPA Modem
Bus 001 Device 005: ID 046d:c00c Logitech, Inc. Optical Wheel Mouse
Bus 001 Device 004: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB
Bus 001 Device 003: ID 413c:0058 Dell Computer Corp. Port Replicator
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

laptop:~$ dmesg | grep 'usb'
[ 0.225371] usbcore: registered new interface driver usbfs
[ 0.225387] usbcore: registered new interface driver hub
[ 0.225418] usbcore: registered new device driver usb
[ 0.504291] usb usb1: configuration #1 chosen from 1 choice
[ 0.504767] usb usb2: configuration #1 chosen from 1 choice
[ 0.505046] usb usb3: configuration #1 chosen from 1 choice
[ 0.505601] usb usb4: configuration #1 chosen from 1 choice
[ 1.061064] usb 1-6: new high speed USB device using ehci_hcd and address 3
[ 1.192636] usb 1-6: configuration #1 chosen from 1 choice
[ 1.447006] usb 2-2: new full speed USB device using uhci_hcd and address 2
[ 1.634908] usb 2-2: configuration #1 chosen from 1 choice
[ 1.708164] usb 1-6.1: new high speed USB device using ehci_hcd and address 4
[ 1.801668] usb 1-6.1: configuration #1 chosen from 1 choice
[ 2.076279] usb 1-6.1.1: new low speed USB device using ehci_hcd and address 5
[ 2.174932] usb 1-6.1.1: configuration #1 chosen from 1 choice
[ 6.580315] usb 1-6.1.2: new high speed USB device using ehci_hcd and address6
[ 6.683479] usb 1-6.1.2: configuration #1 chosen from 1 choice
[ 20.018671] usbcore: registered new interface driver btusb
[ 20.131703] usbcore: registered new interface driver usb-storage
[ 20.131988] usb-storage: device found at 6
[ 20.131991] usb-storage: waiting for device to settle before scanning
[ 20.207981] usb 1-6.1.2: USB disconnect, address 6
[ 20.291499] usbcore: registered new interface driver hiddev
[ 20.297052] input: Logitech USB Mouse as /devices/pci0000:00/0000:00:1d.7/usb1/1-6/1-6.1/1-6.1.1/1-6.1.1:1.0/input/input6
[ 20.297465] generic-usb 0003:046D:C00C.0001: input,hidraw0: USB HID v1.10 Mouse [Logitech USB Mouse] on usb-0000:00:1d.7-6.1.1/input0
[ 20.297534] usbcore: registered new interface driver usbhid
[ 20.297803] usbhid: v2.6:USB HID core driver
[ 26.552360] usb 1-6.1.2: new high speed USB device using ehci_hcd and address 7
[ 26.663506] usb 1-6.1.2: configuration #1 chosen from 1 choice
[ 26.709628] usb-storage: device found at 7
[ 26.709631] usb-storage: waiting for device to settle before scanning
[ 26.732387] usb-storage: device found at 7
[ 26.732390] usb-storage: waiting for device to settle before scanning
[ 31.709568] usb-storage: device scan complete
[ 31.733676] usb-storage: device scan complete

MODEM WORKING

Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 002: ID 046d:c00c Logitech, Inc. Optical Wheel Mouse
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 002: ID 413c:8000 Dell Computer Corp. BC02 Bluetooth Adapter
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 004: ID 12d1:1003 Huawei Technologies Co., Ltd. E220 HSDPA Modem / E270 HSDPA/HSUPA Modem
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

dmesg | grep 'usb'
[ 0.134811] usbcore: registered new interface driver usbfs
[ 0.134826] usbcore: registered new interface driver hub
[ 0.134858] usbcore: registered new device driver usb
[ 0.360327] usb usb1: configuration #1 chosen from 1 choice
[ 0.360783] usb usb2: configuration #1 chosen from 1 choice
[ 0.361061] usb usb3: configuration #1 chosen from 1 choice
[ 0.361611] usb usb4: configuration #1 chosen from 1 choice
[ 1.144122] usb 2-2: new full speed USB device using uhci_hcd and address 2
[ 1.346896] usb 2-2: configuration #1 chosen from 1 choice
[ 1.588072] usb 3-1: new low speed USB device using uhci_hcd and address 2
[ 1.761204] usb 3-1: configuration #1 chosen from 1 choice
[ 5.972042] usb 1-1: new high speed USB device using ehci_hcd and address 4
[ 6.115438] usb 1-1: configuration #1 chosen from 1 choice
[ 19.990565] usbcore: registered new interface driver usbserial
[ 19.991429] usb-storage: device found at 4
[ 19.991432] usb-storage: waiting for device to settle before scanning
[ 20.017260] usbcore: registered new interface driver usb-storage
[ 20.017305] usbcore: registered new interface driver usbserial_generic
[ 20.017308] usbserial: USB Serial Driver core
[ 20.017817] usb-storage: device found at 4
[ 20.017820] usb-storage: waiting for device to settle before scanning
[ 20.070796] usbcore: registered new interface driver btusb
[ 20.229525] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB0
[ 20.229776] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB1
[ 20.229843] usbcore: registered new interface driver option
[ 20.230396] usbcore: registered new interface driver hiddev
[ 20.246280] input: Logitech USB Mouse as /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0/input/input6
[ 20.246438] generic-usb 0003:046D:C00C.0001: input,hidraw0: USB HID v1.10 Mouse [Logitech USB Mouse] on usb-0000:00:1d.1-1/input0
[ 20.246479] usbcore: registered new interface driver usbhid
[ 20.246483] usbhid: v2.6:USB HID core driver
[ 25.436579] usb-storage: device scan complete
[ 25.437674] usb-storage: device scan complete