I'm running MPLAB version 4 and PICSTART version 2.01

Most of the time, I get errors when I try to program a part.
It usually starts programming, but part-way through, I get a message "error
communicating with Picstart Plus".  Sometimes I can get a part programmed,
but it is rare.

This happens with two different machines (one a laptop, the other a
desktop).  Neither one has anything else talking to the serial port.
I have tried different cables.

Has anyone else noticed this problem?  Any ideas?