Embedded library slowing computer?

I have a Windows C++ application using the embedded library.  In it I
perform a couple of queries which take a long time to complete (on the order
of 5-10 minutes).  I have the query executed from a separate thread from the
rest of my UI, but when it is running the UI of my program essentially locks
up (or at least comes very close to it).  The rest of my computer is not
much better in its responsiveness.  I've tried setting the thread priority
of this thread to the lowest possible, but it didn't make any change.
 
Any ideas?
 
Adam Clauss
cabadam@xxxxxxxxxxxxxx