This issue occurs because an InvalidOperationException exception is thrown in the MapiAttachmentProvider.OpenAttachment() function. Then, Windows Error Reporting (WER) starts to work on the exception. Therefore, MSExchangeRPC freezes for about 10 seconds until WER returns control.
For more information about Windows Error Reporting, go to the following Microsoft websites:
For more information about Windows Error Reporting, Problem Reports, and Solutions Feature in Windows 7 and Windows Server 2008 R2, go to the following Microsoft website: