.Dll hell, problems with .Dll files

Hey, I was wondering that you could help me. I have a file in System32 called SiSgrv.dll and its causing some major problems for my directX.

When installing a newer version of direct X it says 'A cabinet file necessary for installation cannot be trusted. Please verify the cartographic services are enabled and the cabinet file certificate is valid.'

I know that the above statement is not specific but after running 'dxdiag' the summary divulges that SiSgrv.dll is the only DirectX file that is not digitally signed. I have tried replacing it but the computer states it is in use by something else.

I tried to replace it using Ms-Dos but the 'sfc' command opens the window for about a maximum of half a second, I assumed that this is because I do not have admin privileges so I changed my account type and there has been no change.

The actual file required is D3D9.dll but that is also present (in use) and obviously faulty (the application states it is unable to load this file). I hoped that re-installing DirectX would solve this problem but it just showed me the above. If anybody could help i would be so grateful.

 

Also I forgot to mention, the application itself stated that a directX update would solve my faulty D3D9.dll file as well as a Direct3D fault. If I wasn't clear before, the D3D9.dll file is also present in my system32 folder and cannot be replaced because it is 'in use by another person or program'

Thanks in advance for any help