We recently upgraded VS 2005 to VS2010 and converted an application seemingly without any problems. But when deployed to the customer they are getting intermittent errors at seemingly random places in the program which force the application to close and AccessViolationExceptions being logged to the Application Event Log.

The customer's site is a multi user environment with the application hosted on a server and users running the app via RDP.

We get two errors in the event log:

Code:
Application: ContainerDepotSystem.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.AccessViolationException
Stack:
   at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr, IntPtr, Int32, IntPtr, IntPtr)
   at System.Windows.Forms.NativeWindow.DefWndProc(System.Windows.Forms.Message ByRef)
   at System.Windows.Forms.ToolTip.WndProc(System.Windows.Forms.Message ByRef)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr, Int32, IntPtr, IntPtr)
   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG ByRef)
   at System.Windows.Forms.Application+ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr, Int32, Int32)
   at System.Windows.Forms.Application+ThreadContext.RunMessageLoopInner(Int

Faulting application name: ContainerDepotSystem.exe, version: 4.0.1.0, time stamp: 0x4d5e6085
Faulting module name: comctl32.dll, version: 5.82.7600.16661, time stamp: 0x4c6f6f53
Exception code: 0xc0000005
Fault offset: 0x0000000000040377
Faulting process id: 0x2920
Faulting application start time: 0x01cbd7f51c53e0d3
Faulting application path: C:\Program Files (x86)\Fargo Systems\Container Yard Manager\ContainerDepotSystem.exe
Faulting module path: C:\Windows\WinSxS\amd64_microsoft.windows.common-controls_6595b64144ccf1df_5.82.7600.16661_none_a44e1fc257f685f6\comctl32.dll
Report Id: d358ca65-43f3-11e0-ac89-0022642b68da
Like I said, everything used to work fine in framework 2.0. Looks like a problem with 4.0.