Blue Screen of Death with EpiValley Photon+ USB Modem

Address: 1000007E, {c0000005, 804e13d5, b40a49ec, b40a46e8}

Well I was getting this BSOD from the day I got the Photon+ USB Modem. I tried calling the Indicom customer support, but I got a standard answer that 'If the card works on my laptop then We cannot help you' hmm the usual answer from any developer. "Hey It works on my environment/system"

I had been quiet busy these days debugging AIX and mainframe dumps, so was living with the BSOD. Finally today I thought to spend some time on the Blue Screen.

Symptoms:
1. BSOD as soon as one plugs in the USB Modem.
2. Well actually this is how to recreate the dump.
Plug in the USB Modem on a running computer and you get a BSOD after the modem is initialized. and before the drive letter is assigned to the USB (Data portion on the same device)
3. If the USB modem is plugged in the computer while restarting then there is no blue screen.

So the suspect was some driver which emulates a CD ROM drive on USB.

Here is the dump what I got. you can use the standard windows WinDbg for debugging crash dumps.
DEFAULT_BUCKET_ID: COMMON_SYSTEM_FAULT

BUGCHECK_STR: 0x7E

LAST_CONTROL_TRANSFER: from 804e13d9 to 804e13d5

STACK_TEXT:
WARNING: Stack unwind information not available. Following frames may be wrong.
b40a4af0 804e13d9 86791020 86c7ed01 00000000 nt+0xa3d5
b40a4b24 ba6db6c5 86791020 0004d014 b40a4be4 nt+0xa3d9
b40a4c30 ba6dcc0f b40a4cd8 00000006 b40a4cb4 drvmcdb+0x56c5
b40a4c8c ba6dd5b5 b40a4cd8 00000006 b40a4cb4 drvmcdb+0x6c0f
b40a4ce4 ba6db3a8 ba6e6cf4 ba6e6df2 ba6e6dfc drvmcdb+0x75b5
b40a4d0c ba6d643c ba6e6db0 ba6e6db2 ba6e6db4 drvmcdb+0x53a8
b40a4d5c 804e1be8 8670a658 ba6dbbab b3c94474 drvmcdb+0x43c
00000000 00000000 00000000 00000000 00000000 nt+0xabe8


FOLLOWUP_IP:
drvmcdb+56c5
ba6db6c5 ?? ???

SYMBOL_STACK_INDEX: 2

SYMBOL_NAME: drvmcdb+56c5

FOLLOWUP_NAME: MachineOwner

IMAGE_NAME: drvmcdb.sys

STACK_COMMAND: .cxr 0xffffffffb40a46e8 ; kb

BUCKET_ID: WRONG_SYMBOLS

Followup: MachineOwner

The problem seems to be with the Drive Letter Access module, since the carsh happens after the modem is initialized and before the drive letter is assigned the the USB drive.

WorkAround.
1. Remove the provider software for drvmcdb.sys :) on my computer it was IBM DLA, others might have it on a different software.

Cons.
Once the driver software for the Photon+ modem is installed you dont need to access the drive. so I am planning to live with not using the data USB feature of the Photon+ for the timebeing.

But, ofc there is no more BSODs :D