USB random error

[Hereoncapecod]

I am using a CCS USB protoboard to supply information back to a VB progran. I used the virtual comm port drivers provided. On some PC's this program runs fine. On others, I am getting a Random error.
Run Time Error 8015, Could not set Comm State, one or more
invalid communications parameters.

I can put an error handler in the VB program to recover from the 8015 message. However, The CCS board needs a hardware reset to recover which is impractical.

1) Any idea what is causing the random error? if so is there any way i can minimize it?
2) Is this going to be a probelm running on Vista?
3) Is there a simple way to reset the USB picc board, I assume watchdog timer in some way, just not sure how to configure it.

Thanks for your help

Bruce