• Looks like it is related to parallelism.

    See below link

    http://blogs.msdn.com/b/bartd/archive/2008/09/24/today-s-annoyingly-unwieldy-term-intra-query-parallel-thread-deadlocks.aspx

    GulliMeel

    Finding top n Worst Performing queries[/url]
    Improve the performance of Merge Join(special case)
    How to Post Performance Problem -Gail Shaw[/url]