Darrel,

As stated, I didn't write the bulk of the code, as both it and the application was written by a friend, who said that back in 2006 it worked fine but on a different chip. I can confirm that he did indeed write the application to function in that way, ie the PIC sends data when it detects the USB connected and then sends updated data back once the update setting button is pressed. I agree a better approach would of been to have the application set the values and then simply update the PIC once the update button has been pressed. I could ask him if he still has the source code and if it can be modified to work that way.

Thanks again for your input.