This looks to be case of denial-of-service attack feature:

This might help:

Solution:

You have to make registry entry to disable the feature:

1. http://support.microsoft.com/?id=899599

Knowledge:

1. http://blogs.msdn.com/sql_protocols/archive/2006/04/12/574608.aspx

2. http://support.microsoft.com/?id=899599

I am...