DLL Inialization Failures While Logging Off

We just recently bought the Dimension 8400 Media Center.  Almost immediately, (during the log off process) error messages like :  "dwwin.exe - DLL Inialization Failed.  The application failed to initialize because the window station is shutting down", began to show up.  Sometimes a second message would pop up on top of this like "tfswctrl.exe - Application Error: The instruction at 0X77f16a73 referenced memory at 0x004f63da.  The memory could not be read".  Many times I would not be able to log off (because the system would be frozen).  During one of these events the computer logged back on with no icons and completely frozen.  I shut it off again and upon restart the hard drive failed.  Two weeks later, we now we have a new hard drive and everything has been re-installed.  Tonight, lo and behold, this message "dwwin.exe - DLL Inialization Failed.  The application failed to initialize because the window station is shutting down", appeared again.  Obviously I am a little more than nervous.  I don't understand much of what is going on with this computer and am hoping someone has come across this problem - and might know how to fix it.  I have looked over these boards and have seen where people have single DLL inialization failures, but I don't see where anyone has had multiple, different DLL failures.  (Some of the other failures that have shown up on my system are:  rng.exe - DLL Initialization Failed and DSLog.exe - DLL Inialization Failed).  My questions are:  is this a problem to be concerned with, is there a fix for this problem and should I be concerned about the hard drive failing again?

 

Any help would be appreciated...

Cindy