[AccessD] Cannot Create Output File

Hey All
I have a form in an 2003 application that allows the user to zip/unzip files
relating to a project. I am Shelling out to the Windows zip program.
Everything basically works fine, but the odd time in the
archiving/compressing of the files a message box from the zip program pops
up  "Cannot Create Output File".
 
1. Can someone tell me what this means ( I have tried Goggling for an
explanation)?
2. Because the message is outside the application sometimes when I click the
button in the message box it locks up my application. I have tried to close
it in Access code but of course to no avail as Access is not controlling the
program.  Any suggestions?
 
Thanks
Tony Septav
Nanaimo, BC
Canada