A. These are a sign that SQL Server has had a "handled access violation" - a gpf.
The dump files contain information on what SQL Server was doing at the time, module stack traces etc. Though there is a PRINTDMP.EXE utility supplied the output of this is of no use to anyone unless they have the SQL Server C source code - which no-one outside the Microsoft development/support teams does.
Save the dumps away, together with errorlog info, what SQL was running at the time etc. and contact Microsoft PSS for support in resolving the problem. See mspss.txt in the faq for more information on Microsoft PSS. (Before calling make sure that the problem still occurs when you are running the latest service pack and that dbcc healthchecks on the database report no problems)