Hmmm. First off, you should never have to click "proceed" when switching disks. The OS will autodetect the disk change and kill the requestor for you. However that being said, clicking proceed, while being unnecessary, should still work unless you're clicking proceed too quickly and the OS hasn't recognized the diskchange yet.
If you don't run the installer and swap disks. Does the Workbench recognize the diskchange? If not you can try opening the Shell and typing "Diskchange DF1:" That should force the OS to recheck the disk inserted into DF1: