WLANExt.exe crashes after connecting to printer by Wi-Fi for several hours

Question

When I connect to my Brother HL-2170W to print a document, and I stay connected for several hours, WLANExt.exe (Windows Wireless LAN 802.11 Extensibility Framework) begins to max out one CPU core and allocate large amounts of memory, causing a major system slowdown due to paging, and eventually crashes. The computer is subsequently disconnected from the printer, and I cannot remain connected to the printer for an extended period of time as a result. My computer is running Windows 7 Home Premium Service Pack 1 64-bit and is connected to the printer ad-hoc without a router. Why does WLANExt do this, and what can I do about it?

Problem information from Action Center Reliability Monitor is as follows:

Source
Windows Wireless LAN 802.11 Extensibility Framework

Summary
Stopped working

Date
‎4/‎10/‎2011 10:16 PM

Status
Report sent

Description
Faulting Application Path:  C:\Windows\System32\wlanext.exe

Problem signature
Problem Event Name: APPCRASH
Application Name:   WLANExt.exe
Application Version:    6.1.7600.16385
Application Timestamp:  4a5bcc33
Fault Module Name:  MSVCR80.dll
Fault Module Version:   8.0.50727.4940
Fault Module Timestamp: 4ca2b4dd
Exception Code: c0000005
Exception Offset:   000000000001e460
OS Version: 6.1.7601.2.1.0.768.3
Locale ID:  1033
Additional Information 1:   11a6
Additional Information 2:   11a6764bdad9592045f504cfd8eeedc0
Additional Information 3:   b65b
Additional Information 4:   b65b2b58d41cae3925ea5162417c3337

Extra information about the problem
Bucket ID:  27322072

Edit: I've noticed that WLANExt.exe may crash after being connected to the printer for variable periods of time, ranging from less than 30 minutes to more than 12 hours. It appears that this problem may be related to the system attempting to gain Internet access through the device, which is impossible since the printer is not connected to a router. However, this does not always happen whenever the system says "Identifying" for the printer in the network connections icons in the notification area. The exception code c0000005 indicates an access violation (segfault). I still cannot determine what would trigger this behavior, and the fact that WLANExt.exe allocates large amounts of memory (2GB or more) before crashing makes this a very odd issue to understand. Additionally, the system often indicates that the signal strength is very weak, even if the computer is mere inches away from the printer. Any idea as to what the problem is?

Answer 1

Please update your Wireless and Printer drivers prior to doing any further troubleshooting, to ensure that you have an actual problem and it's not just your drivers that are out of date and thus unstable. As there is an access violation, it might also be of your interest to ensure your memory and hard drive are fine by doing error scans on them...

Check if the event log or the reliability monitor lists a crash dump for the moment of the crash.

Besides the moment of crash, you would also like to know what is causing the CPU to spike, so you will also need a hang dump of that moment. These can easily be caught with ProcDump, by for example typing:

procdump WLANExt.exe -c 25 -s 4 WLANExt.dmp

Although this will capture the moment, it could also be interesting to capture the whole thing. This will allow us to see any I/O, Page Faults, Interrupts, DPCs, Events and many small other things that could be occuring during the hang resulting in a crash. Just follow the procedure I described here and stop capturing once it has crashed, it's configured by default to only remember the last X seconds so don't worry about resources...

So, when you collected these three crash/trace dumps, you can analyze them with WinDBG and XPerf or pass it along to me and I'll try to show you where things go wrong...