Some filenames are not supported by Windows
Windows OS reserve characters more than any other operating system for creating a filename. Due to this, if your computer files contain characters that are forbidden by Windows OS then they will be considered as invalid filenames. Although operating system itself won't allow you to create a filename containing forbidden characters, yet you can see these type of files in a directory since they can be created automatically by the system. Here are the characters given below that are considered as invalid for filenames:
- < (less than)
- > (greater than)
- : (colon)
- " (double quote)
- / (forward slash)
- \ (backslash)
- | (vertical bar or pipe)
- ? (question mark)
- * (asterisk)
Furthermore, Windows OS doesn't differentiate between upper case & lower case so you can't have two files having the same name in a directory.
Why CHKDSK attempts to delete invalid filenames?
As discussed above OS doesn't allow you to create a filename with invalid characters, if anyhow they are created then CHKDSK attempts to delete them as soon as it runs. Moreover, while scanning a hard disk, if CHKDSK come across a file containing invalid filename in directory then it displays a message as shown below in both command line and GUI of Check Disk.
