HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Taskband, Value type is DWORD, Value name is NumThumbnails, Data can be set to 0
If Google doesn't help
You don't say anything about crash . If app hangs it's because SHAppBarMessage waits for taskbar to reply; you need to capture explorer.exe dump in that exact moment: task manager - details - (heaviest) explorer.exe - Create memory dump file