Currently, if you right-click on a Mac-formatted disk in Windows Explorer and use Windows' option to "Format...", then format the disk as NTFS, our disk protection dialog box does not pop up as expected.  This disk protection dialog box is intended to help protect users from inadvertently formatting a Mac disk and losing data and asks for confirmation of changes.  Because of this issue, when the disk is formatted, the Mac partitioning data will be retained but the disk will contain an NTFS volume.  While this will work normally with MacDrive installed, because of the Mac partitioning data, the disk will not mount on a computer without MacDrive installed.  This is not intentional behavior in MacDrive and we plan a fix for this behavior in a future release.

If you have already created a disk of this type and need to access it, one simple workaround is to download and install the MacDrive trial version.  Installing MacDrive will work for accessing disks affected by this problem regardless of license state, including if the trial is expired.  After installing MacDrive and restarting the computer when prompted, please ignore any licensing prompts and go to Start > Computer.  The disk should now be mounted.  You can then recover the data from the disk.  

To avoid this problem, if you have a Mac-formatted disk that you wish to reformat as NTFS, please do so through Windows Disk Management.  To access this, open the Start menu, right click on "Computer" (or "My Computer", depending on Windows version) and select "Manage".  Under the category "Storage", select "Disk Management".   Locate the Mac-formatted disk on the list of available disks and right-click on the disk from within the "Volume" column.  Select "Format" to format the disk.