I’m assuming this is already done with FRST, but to ensure;

Control Panel > Appearance and Personalization > Under “Folder Options” hit Show Hidden Files and Folders.

Ensure that the Radiobutton "Show Hidden Files; Folders & Drives is checked.
Ensure that "Hide Extensions for Known File Types is UN-checked.
Ensure that "Hide protected operating system files (Recommended) is UN-Checked.

Note; for the last, you will be prompted confirming your decision. Hit Yes. Now, recheck the C:\ for any Greyed (Ghosted) folders named ATI.