Normally, when a disk is mounted to a drive letter (via OSFMount or another mount tool) in Windows, the files and folders of the file system is accessible in Windows Explorer. In some cases, however, Windows does not recognize the file system on the partition and the user is prompted with an error message and/or a prompt to format the disk. This can occur because of the following:
- The mounted drive does not contain a Windows-recongizable file system (ie. NTFS/FAT)
- The file system is corrupted
- The file system permissions prevent the drive from being accessed
If you are absolutely sure that the drive contains a Windows-recognizable, non-corrupted file system and the drive is mounted as read-only, there is a chance that the security permission (ownership) of the file system is blocking the drive from being accessed. In some cases, this can be reset automatically by mounting the drive as read-write. Of course, you should always make backup copies of the drive before mounting it as read-write.
If there is no need to mount the drive in Windows but you still want to access the contents of the drive, you can use OSForensics to explore the files/folders of the drive without mounting it to a Windows drive letter. Simply add the image file to the case, then use the File System Browser to browse the files and folders in the image file.