Cannot disable Sophos 10 LSP

We're having issues disabling the Sophos 10 64-bit LSP using the following command:

C:\ProgramData\Sophos\Web Intelligence\swi_lsp32_util.exe -u -d swi_ifslsp_64.dll 

This works on he 32-bit version, but not the 64. After running the above command we get the following error:

retrieveLSPGUID: LoadLibraryA(swi_ifslsp_64.dll) failed: 193

Has anyone run into this before? Google didn't have much to say about that error. 

Thanks in advance. 

EDIT:

I forgot to add that I also tried using Windows 7 regsvr32 /u, but it did not work. I got the following error:

The module "C:\Program Data\Sophos\Web Intelligence\swi_ifslsp_64.dll" failed to load.

Make sure the binary is stored at the specified path or debug it to check for problems with the binary or dependent .DLL files.

The specified module could not be found.