Norton Utilities 15 doesn't recognize Firefox

When using the Disc Clean function, NU15 shows Firefox as being not Installed.

 

I'm using:

- Firefox 7.0.1

- NU15: Version: 15.0.0.122, Engine 3.0.0.854, Framework: 3.0.0.700. (fully updated).

- Windows 7 Home Premium  (Service Pack 1 / fully updated).

 

- Win7 (64-bit) is on it's own SSD (OS)

- NU15 is on it's own SSD (Programs).

- All temporary, Temp/TMP and Archive files/folders are on a third standard HDD (10.000rpm).

 

- Both SSDs & the HDD are SATA3.

- The CPU is an AMD Phenom II x4 980 @ 3.7GHz.

- Have 8GB of memory.

 

What can I do to get NU15 to recognize Firefox?