Now I can neither extract files to nor delete the folder because it is "corrupted and unreadable". This is the first time I have had such a problem come up and it is rather disturbing.

The Disk structure is corrupted and unreadable When you see this error, it may mean that the storage media – may be your USB, Memory Card or External Drive is facing some problem.

Is it supposed to do that, or can it just fix errors and not delete things? Does it actually delete corrupt files, or does it try to fix them and then deletes them if they can't be fixed?

What Does It Mean When Your File Is Corrupt?. Just about every computer user has encountered a problem opening a program or file.

Fix Excel found unreadable content, Do you want to recover the contents of this document error when opening a workbook, with these fixes.