Freeze up - Sony Vaio

Question

I'm interested in finding out how to troubleshoot my Vaio (PCG-FX200) notebook.  It has recently began freezing up.  It freezes solid.  The only way to get it to re-boot is to pull the battery, which I hate to do.  I have done all the routine maintenance chores, plus ran the Dr. Watson program.  It gives a reference to "MStask" running strangely in the task bar and instructs to shut that program down.  This has become more than a nuisance here of late.  Any suggestions for a solution? thanks TC