Go to HKEY_CLASSES_ROOT\CLSID\{20D04FE0-3AEA-1069-A2D8-08002B30309D}
Change the value of LocalizedString to:
%USERNAME% on %COMPUTERNAME%
(or whatever you’d like it to read)
(default value is: @%SystemRoot%\system32\SHELL32.dll,-9216)
via Rename the My Computer Icon Label with Useful Info | Symantec Connect Community.