What is running when the stack dump generates? Non-yielding resources usually mean that something pre-emptive was executing which could be CLR, an XP, a OLE Automation Call, or it could be a real bug in SQL Server, that you've happened upon in your configuration. It is not impossible. You might read the PSS teams blog post on the non-yielding resource monitor:

http://blogs.msdn.com/psssql/archive/2008/03/28/how-it-works-non-yielding-resource-monitor.aspx">

http://blogs.msdn.com/psssql/archive/2008/03/28/how-it-works-non-yielding-resource-monitor.aspx

There is a whitepaper linked at the top of the post that has information on how to actually read the dump file with the debugger to determine what actually caused it to dump out. It gets really cryptic though, and support is likely your best avenue to a fix for this problem.