Welcome to the forum, decard; I think I can relate to this, if not help your installation or respond directly. I recently found that indeed I could not delete/erase/"EXCLUDE" the C drive reference/location from the Edit Preferences/Library/monitored folders box on my Surface Pro installation [I could no longer fit my collection in my 256Gb Surface Pro C drive and now had/have to reference D, a "removable" drive, instead (its SD card slot)]. I decided to finally uninstall and reinstall MB, and on re-installation I was able to set D:\Music as my library folder in that monitor box to be scanned. There may well have been more efficient or direct ways to resolve my issue, frankz, but I couldn't find it. (All this references MB Installer versions, in case this matters.) Good luck resolving your issue, decard.