It's because of how you exit your smaller While loop. Your logic is set up so that if the user double-clicks on the listbox OR clicks on "Save" OR clicks on "Cancel" OR there is an error, the program exits the loop. The next piece of the program to run is dependent on the output of the Dbl-Click property - even if that isn't what the user clicked on! So in those cases you get a value of 0 from Dbl-Click and the program falls apart when it uses this 0 in the part that builds pathnames and you end up with a bad path that it then tries to tack the value of the "Save As" control onto.
I think your program would benefit from a bit more thought about its structure. If it was based around an Event structure or a State Machine, you would be able to know exactly what the user had clicked on, rather than that they'd just clicked on *something* and be really specific about what code gets run in each case. Hope this helps, James.
