If your Windows explorer crashes when performing any taskbar-related operation in Windows 7 or in Windows Server 2008 R2 like say pinning or unpinning icons or dragging links to the taskbar, then you can apply this just-released hotfix from Microsoft and see if it resolves your problem.

Details: KB2515325.

Also read: Windows 7 or Vista Explorer Crashes Or Freezes Frequently. | WinVistaClub.