[Galaxy S II Q&A, Help & Troubleshooting] Tungstwenty:
My phone is not connecting successfully to the latest Kies installed on a PC.

The "connecting ..." message just shows for a considerable amount of time and then I get the error "Cannot start service on the device. Please disconnect and reconnect"

I've seen that on S3 the kies service is explicitly disabled, but on Siyah for S2 I searched the threads but didn't find anything relevant.

Here's an excerpt of the logcat during the connection attempt (it's the same whether USB debugging is ON or OFF):

E/DataRouter( 1910): usb connection is true
E/DataRouter( 1910): DSR is ON. Don't send DTR ON.
E/DataRouter( 1910): usb connection is true
E/DataRouter( 1910): DSR is ON. Don't send DTR ON.
E/DataRouter( 1910): After the usb select
E/DataRouter( 1910): Before checking the modem suspend state
E/DataRouter( 1910): PDP is resumed now
E/DataRouter( 1910): After checking the modem suspend state
E/DataRouter( 1910): Path check Path is 0
E/DataRouter( 1910): Got command as string
E/DataRouter( 1910): last char is 10
E/DataRouter( 1910): last second char is 13
E/DataRouter( 1910): IsDeviceManagerCmd buffer in usb = AT+DEVCONINFO
E/DataRouter( 1910):
E/DataRouter( 1910): Data Path Found is DEVICE MANAGER
E/DataRouter( 1910): Path set is DATA_PATH_DR_DEVICE_MANAGER
E/DataRouter( 1910): Message:AT+DEVCONINFO
E/DataRouter( 1910):
E/DataRouter( 1910): processing AT command of length 15
E/DataRouter( 1910): -------- buffer is =AT+DEVCONINFO
E/DataRouter( 1910):
E/DataRouter( 1910): Connection Information Request
E/DataRouter( 1910): [DEVCONINFO]MN(GT-I9100);(len:13)
E/DataRouter( 1910): [DEVCONINFO]BASE(GT-I9100);(len:15)
E/DataRouter( 1910): [DEVCONINFO]GT-I9100(len:8)
E/DataRouter( 1910): [DEVCONINFO]I9100XWLPG(len:10)
E/DataRouter( 1910): [DEVCONINFO](null)
E/DataRouter( 1910): [DEVCONINFO]++++++
E/DataRouter( 1910): [DEVCONINFO]I9100XXLPX(len:10)
E/DataRouter( 1910): [DEVCONINFO]++++++
E/DataRouter( 1910): [DEVCONINFO] ril.official_cscver (len:0)
E/DataRouter( 1910): [ret DEVCONINFO]AT+DEVCONINFO
E/DataRouter( 1910): +DEVCONINFO: BUSY(len:32)
E/DataRouter( 1910): write [32] bytes of data to USB fd[0]
E/DataRouter( 1910): write [6] bytes of data to USB fd[0]
E/DataRouter( 1910): Change pass DTT --4 0
E/DataRouter( 1910): Change pass DTT 4 0
E/DataRouter( 1910): Before the usb select
E/DataRouter( 1910): usb connection is true
E/DataRouter( 1910): DSR is ON. Don't send DTR ON.
E/DataRouter( 1910): After the usb select
E/DataRouter( 1910): Before checking the modem suspend state
E/DataRouter( 1910): PDP is resumed now
E/DataRouter( 1910): After checking the modem suspend state
E/DataRouter( 1910): Path check Path is 0
E/DataRouter( 1910): Got command as string
E/DataRouter( 1910): last char is 10
E/DataRouter( 1910): last second char is 13
E/DataRouter( 1910): IsDeviceManagerCmd buffer in usb = AT+DEVCONINFO
E/DataRouter( 1910):
E/DataRouter( 1910): Data Path Found is DEVICE MANAGER
E/DataRouter( 1910): Path set is DATA_PATH_DR_DEVICE_MANAGER
E/DataRouter( 1910): Message:AT+DEVCONINFO
E/DataRouter( 1910):
E/DataRouter( 1910): processing AT command of length 15
E/DataRouter( 1910): -------- buffer is =AT+DEVCONINFO
E/DataRouter( 1910):
E/DataRouter( 1910): Connection Information Request
E/DataRouter( 1910): [DEVCONINFO]MN(GT-I9100);(len:13)
E/DataRouter( 1910): [DEVCONINFO]BASE(GT-I9100);(len:15)
E/DataRouter( 1910): [DEVCONINFO]GT-I9100(len:8)
E/DataRouter( 1910): [DEVCONINFO]I9100XWLPG(len:10)
E/DataRouter( 1910): [DEVCONINFO](null)
E/DataRouter( 1910): [DEVCONINFO]++++++
E/DataRouter( 1910): [DEVCONINFO]I9100XXLPX(len:10)
E/DataRouter( 1910): [DEVCONINFO]++++++
E/DataRouter( 1910): [DEVCONINFO] ril.official_cscver (len:0)
E/DataRouter( 1910): [ret DEVCONINFO]AT+DEVCONINFO
E/DataRouter( 1910): +DEVCONINFO: BUSY(len:32)
E/DataRouter( 1910): write [32] bytes of data to USB fd[0]
E/DataRouter( 1910): write [6] bytes of data to USB fd[0]
E/DataRouter( 1910): Change pass DTT --4 0
E/DataRouter( 1910): Change pass DTT 4 0
E/DataRouter( 1910): Before the usb select
E/DataRouter( 1910): usb connection is true
E/DataRouter( 1910): DSR is ON. Don't send DTR ON.

Can anyone running a similar configuration to mine (stock 4.0.3, siyah 5.0.1) confirm if it's running ok for them?

If it isn't the kernel, this might be a ROM issue or something related with the CSC (although the failure is immediately at the connection stage and not in the update checks). The line saying "ril.official_cscver (len:0)" might be unexpected.