I have a similar issue with Win7 wireless connectivity, occurring randomly when disconnecting from one network then connecting to a different network. The Tray icon would freeze. The Issue appears to minimize when I close any apps using the network, such as internet, external USB drives etc. Also seemed to occur less when using Task Manager open in the Network Tab to ensure that there was no network traffic at the time of disconnecting/connecting. It may just be that I was allowing time for the overflow in the message buffer to not occur viz the following.
The following explanation seems most likely, and I am going to try Microsoft's suggestion:
However, a workaround is available. Try reconnect to Wireless LAN again after Explorer automatically restarts. Trying in a place where there are less than 5 access points is more successful
Microsoft explained that, under certain conditions, Windows Explorer in the latest iteration of the Windows client might crash when users attempt to connect a wireless network. According to the Redmond company, customers that have come across this issue indicated that the crashes were caused by nothing more than simple attempts to connect Wireless LAN from the tray icon. In this scenario, Windows Explorer will crash, only to subsequently restart. At the same time, an error message is stored in the Application log. Users will be able to find the message at the bottom of this article, or on Microsoft Support.
“This issue tends to occur when you select a Wireless LAN from 5 or more access points. (…) This problem occurs because the message handling for Wireless connection is not fast enough and causes overflow in the message queue,” Microsoft explained.
The Redmond company has even documented the necessary steps to reproduce the problem. Users need only to click one Wireless LAN connection from the tray icon and enter the Security Key in the connection dialog window. Double clicking the OK button will cause Windows Explorer to crash and restart.
Microsoft doesn’t yet have an update designed to resolve the issue. The software giant isn’t even offering end users affected by the glitch a hotfix to help them out. However, a workaround is available. “Try reconnect to Wireless LAN again after Explorer automatically restarts. Trying in a place where there are less than 5 access points is more successful,” Microsoft noted.
Here is the event message that’s logged in the Application log when this issue occurs, according to Microsoft:
“Log Name: Application
Source: Application Error
Event ID: 1000
Task Category: (100)
Faulting application name: Explorer.EXE、version: 6.1.7600.16385、time stamp: 0x4a5bc60d
Faulting module name: WLanConn.dll、version: 6.1.7600.16385、time stamp: 0x4a5bdb56
Exception code: 0xc0000005
Fault Offset: 0x0001396d
Faulting process id: 0x608
Faulting application start time: 0x01ca6d66f0810815
Faulting application path: C:\Windows\Explorer.EXE
Faulting module path: C:\Windows\system32\WLanConn.dll.