[ramanandji]

Description:
I have WINDOWS XP SP2 and Mobile Handset LG M4410 with Data Cable and a GPRS service from Airtel India. When I connect to Internet through data cable using the above mobile as modem, gets connected to net successfully. When I try to open any site just for a minute the data is downloaded and immediately CPU usage goes up to ~95%. And no more data transfer happens and CPU Fan makes lot of noise indicating heavy load. The computer almost hangs thereafter. Unless I disconnect datacable manually computer will not come to normal state.

I have observed the following things using PROCESS EXPLORER from systeminternals.com:

[1] It is svchost.exe which eats up CPU time. This file has lot services attached to it. I tried disabling all of them except RasMan.exe(Remote Access Connection Manager). Still the problem is seen, so I conclude that problem due to this service only.

[2] I have observed the threads also. This particular thread "kernel32.dll!CreateThread+0x27" causes lot of context switches. The CSwitchDelta oscillates between 150-200.

[3]This thread only eats 95% of CPU.

[4]No virus as far as I know. Because after formatting and reloading of XP also I obeserved the same problem.

[5]There is no problem if connect to Internet through bluetooth, I have browsed for hours but CPU usage never jumped to 95%. Only if connected through data cable it the problem is seen.

[6]I believe this problem is with LG Data Cable only, as I used Nokia3220 and Nokia6610i as modems and CA-42 serial cable to connect to Internet and browsed for hours but CPU usage never jumped to those levels(~95%).

Stack for this thread:

(a)
When connected to Internet and after CPU usage jumps to 95%:
------------------------------------------------------------
ntkrnlpa.exe!KiDispatchInterrupt+0x7f
ntkrnlpa.exe!KeReleaseInStackQueuedSpinLockFromDpc Level+0xaab
ntdll.dll!KiFastSystemCallRet
tapisrv.dll+0x181ed
tapisrv.dll+0x18ba4
tapisrv.dll+0x2055e
RPCRT4.dll!CheckVerificationTrailer+0x75
RPCRT4.dll!NdrStubCall2+0x215
RPCRT4.dll!NdrServerCall2+0x19
RPCRT4.dll!NdrGetTypeFlags+0x1c9
RPCRT4.dll!NdrGetTypeFlags+0x12e
RPCRT4.dll!NdrGetTypeFlags+0x5a
RPCRT4.dll!NdrConformantArrayFree+0x42e
RPCRT4.dll!NdrConformantArrayFree+0x28b
RPCRT4.dll!I_RpcBCacheFree+0x14c
RPCRT4.dll!I_RpcBCacheFree+0x5ea
RPCRT4.dll!I_RpcBCacheFree+0x403
RPCRT4.dll!I_RpcBCacheFree+0x5d2
kernel32.dll!GetModuleFileNameA+0x1b4

(b)
After disconnection by removing datacable CPU usage comes down to 1-3%
----------------------------------------------------------------------

ntkrnlpa.exe!KiUnexpectedInterrupt+0xf0
ntkrnlpa.exe!NtConnectPort+0x1cc8
ntkrnlpa.exe!NtConnectPort+0x1efc
ntkrnlpa.exe!KeReleaseInStackQueuedSpinLockFromDpc Level+0xb14
ntdll.dll!KiFastSystemCallRet
shsvcs.dll+0x18217
shsvcs.dll+0x17b33
svchost.exe+0x11cc
ADVAPI32.dll!CryptVerifySignatureW+0x29
kernel32.dll!GetModuleFileNameA+0x1b4


Can somebody help me what shall I do to rectify this problem?


Similar stack traces repeatedly taken for clarity are given below;

Not yet Connected to Net, CPU Usage:Normal
------------------------------------------
ntkrnlpa.exe!KiUnexpectedInterrupt+0xf0
ntkrnlpa.exe!NtWriteFile+0x2b00
ntkrnlpa.exe!NtReadFile+0x580
ntkrnlpa.exe!KeReleaseInStackQueuedSpinLockFromDpc Level+0xb14
ntdll.dll!KiFastSystemCallRet
ADVAPI32.dll!SetServiceStatus+0x238
ADVAPI32.dll!SetServiceStatus+0xcc
ADVAPI32.dll!StartServiceCtrlDispatcherW+0x8b
svchost.exe+0x2585

Connected, CPU Usage:~95%
-------------------------
ntkrnlpa.exe!KiDispatchInterrupt+0x7f
ntdll.dll!KiFastSystemCallRet
kernel32.dll!WaitForSingleObject+0x12
tapisrv.dll+0x18ab4
tapisrv.dll+0x19494
tapisrv.dll+0x20ede
RPCRT4.dll!CheckVerificationTrailer+0x75
RPCRT4.dll!NdrStubCall2+0x215
RPCRT4.dll!NdrServerCall2+0x19
RPCRT4.dll!NdrGetTypeFlags+0x1c9
RPCRT4.dll!NdrGetTypeFlags+0x12e
RPCRT4.dll!NdrGetTypeFlags+0x5a
RPCRT4.dll!NdrConformantArrayFree+0x42e
RPCRT4.dll!NdrConformantArrayFree+0x28b
RPCRT4.dll!I_RpcBCacheFree+0x14c
RPCRT4.dll!I_RpcBCacheFree+0x5ea
RPCRT4.dll!I_RpcBCacheFree+0x403
RPCRT4.dll!I_RpcBCacheFree+0x5d2
kernel32.dll!GetModuleFileNameA+0x1b4

Disconnected, CPU Usage:Normal
------------------------------
ntkrnlpa.exe!KiUnexpectedInterrupt+0xf0
ntkrnlpa.exe!NtConnectPort+0x1cc8
ntkrnlpa.exe!KeReleaseInStackQueuedSpinLockFromDpc Level+0xb14
ntdll.dll!KiFastSystemCallRet
RPCRT4.dll!I_RpcBCacheFree+0x5ea
RPCRT4.dll!I_RpcBCacheFree+0x403
RPCRT4.dll!I_RpcBCacheFree+0x5d2
kernel32.dll!GetModuleFileNameA+0x1b4

Connected, BUT CPU Usage has not yet JUMPED to 95%(within ~1min time)
---------------------------------------------------------------------
ntkrnlpa.exe!KiUnexpectedInterrupt+0xf0
ntkrnlpa.exe!IoSetIoCompletion+0x2c9
ntkrnlpa.exe!KeReleaseInStackQueuedSpinLockFromDpc Level+0xb14
ntdll.dll!KiFastSystemCallRet
RPCRT4.dll!I_RpcBCacheFree+0xcc2
RPCRT4.dll!I_RpcBCacheFree+0xbf3
RPCRT4.dll!I_RpcBCacheFree+0xd71
RPCRT4.dll!I_RpcBCacheFree+0x403
RPCRT4.dll!I_RpcBCacheFree+0x5d2
kernel32.dll!GetModuleFileNameA+0x1b4

Connected, CPU Usage:~95%
-------------------------
ntkrnlpa.exe!KiDispatchInterrupt+0x7f
ntdll.dll!KiFastSystemCall
kernel32.dll!WaitForSingleObject+0x12
tapisrv.dll+0x18ab4
tapisrv.dll+0x19494
tapisrv.dll+0x20ede
RPCRT4.dll!CheckVerificationTrailer+0x75
RPCRT4.dll!NdrStubCall2+0x215
RPCRT4.dll!NdrServerCall2+0x19
RPCRT4.dll!NdrGetTypeFlags+0x1c9
RPCRT4.dll!NdrGetTypeFlags+0x12e
RPCRT4.dll!NdrGetTypeFlags+0x5a
RPCRT4.dll!NdrConformantArrayFree+0x42e
RPCRT4.dll!NdrConformantArrayFree+0x28b
RPCRT4.dll!I_RpcBCacheFree+0x14c
RPCRT4.dll!I_RpcBCacheFree+0x5ea
RPCRT4.dll!I_RpcBCacheFree+0x403
RPCRT4.dll!I_RpcBCacheFree+0x5d2
kernel32.dll!GetModuleFileNameA+0x1b4

Disconnected, CPU Usage:Normal
------------------------------
ntkrnlpa.exe!KiUnexpectedInterrupt+0xf0
ntkrnlpa.exe!NtConnectPort+0x1cc8
ntkrnlpa.exe!KeReleaseInStackQueuedSpinLockFromDpc Level+0xb14
ntdll.dll!KiFastSystemCallRet
RPCRT4.dll!I_RpcBCacheFree+0x5ea
RPCRT4.dll!I_RpcBCacheFree+0x403
RPCRT4.dll!I_RpcBCacheFree+0x5d2
kernel32.dll!GetModuleFileNameA+0x1b4


Connected, BUT CPU Usage has not yet JUMPED to 95%(within ~1min time)
---------------------------------------------------------------------

ntkrnlpa.exe!KiUnexpectedInterrupt+0xf0
ntkrnlpa.exe!NtConnectPort+0x1cc8
ntkrnlpa.exe!NtConnectPort+0x1efc
ntkrnlpa.exe!KeReleaseInStackQueuedSpinLockFromDpc Level+0xb14
ntdll.dll!KiFastSystemCallRet
shsvcs.dll+0x18217
shsvcs.dll+0x17b33
svchost.exe+0x11cc
ADVAPI32.dll!CryptVerifySignatureW+0x29
kernel32.dll!GetModuleFileNameA+0x1b4

Connected, CPU Usage:~95%
-------------------------

ntkrnlpa.exe!KiDispatchInterrupt+0x7f
ntkrnlpa.exe!ProbeForRead+0x160f
ntkrnlpa.exe!KeReleaseInStackQueuedSpinLockFromDpc Level+0xb14
ntdll.dll!KiFastSystemCallRet
tapisrv.dll+0x181ed
tapisrv.dll+0x18ba4
tapisrv.dll+0x2055e
RPCRT4.dll!CheckVerificationTrailer+0x75
RPCRT4.dll!NdrStubCall2+0x215
RPCRT4.dll!NdrServerCall2+0x19
RPCRT4.dll!NdrGetTypeFlags+0x1c9
RPCRT4.dll!NdrGetTypeFlags+0x12e
RPCRT4.dll!NdrGetTypeFlags+0x5a
RPCRT4.dll!NdrConformantArrayFree+0x42e
RPCRT4.dll!NdrConformantArrayFree+0x28b
RPCRT4.dll!I_RpcBCacheFree+0x14c
RPCRT4.dll!I_RpcBCacheFree+0x5ea
RPCRT4.dll!I_RpcBCacheFree+0x403
RPCRT4.dll!I_RpcBCacheFree+0x5d2
kernel32.dll!GetModuleFileNameA+0x1b4

Disconnected, CPU Usage:Normal
------------------------------

ntkrnlpa.exe!KiUnexpectedInterrupt+0xf0
ntkrnlpa.exe!NtConnectPort+0x1cc8
ntkrnlpa.exe!KeReleaseInStackQueuedSpinLockFromDpc Level+0xb14
ntdll.dll!KiFastSystemCallRet
RPCRT4.dll!I_RpcBCacheFree+0x5ea
RPCRT4.dll!I_RpcBCacheFree+0x403
RPCRT4.dll!I_RpcBCacheFree+0x5d2
kernel32.dll!GetModuleFileNameA+0x1b4