I am using SheepShaver on Windows 10, and I enabled the option that allows SheepShaver to put a My PC icon so I could access files from my actual PC. However, when I try to drag files from My PC to the SheepShaver desktop, I can't because it says the folder is write protected. How can I make it not write protected?
The desktop was handled oddly in Classic Mac OS. Every non-removable drive had its own Desktop Folder, and the contents of those folders from every mounted disk were displayed together on the desktop. By default, dragging a file from any disk to the desktop would attempt to move it to that drive's Desktop Folder, rather than copying it to another disk.
From what you're describing, it sounds like the "My PC" drive is treated as a local drive, but it is either read-only, or cannot have a Desktop Folder created.
As a workaround, create a folder on the desktop -- by default, this will be created on your startup disk -- then drag your file into that folder to copy it to that disk. Once you've copied the file, you can move it back out to the desktop if you so desire.
See if it makes a difference by right-clicking on your folder in Windows and click on "Properties", then un-check the "Read-only" attribute.
Or alternatively, reset the attributes from a command prompt replacing "?" with your drive letter and "folder name" with your folder name.
attrib -h -r -s /s /d ?:\folder name\*.*