not signed files in SIGVERIF report

Hi, I have to un-signed files listed here.

[c:\program files\common files\microsoft shared\vgx]
vgx.dll 26/06/2007 6.0.2900.3164 Not Signed
N/A

win32k.sys 19/03/2008 5.1.2600.3335 Not Signed
N/A

It is safe to keep this files as such or what should I do to correct the
problem ?

Thanks to whoever will answer my inquiry,
Charles A. Gilbert