Problem with NIS - sluggush computer

I noticed my hard drive being accessed continuously and my computer is very sluggish.  This is a newer issue.  I determined nis.exe*32 was performing an excessive numbers of I/O read and writes (millions).  There are two instances of nis running, one under my user name and one under system.  The system instance has the excessive I/o read/writes.  I cannot stop either process.

I have NIS version 21.6.0.32. 

I have Widows 7 64-bit.  I7 processor @3.4GHz w/8G RAM.

What could be causing the problem?