ASP.NET COM Error

I have an ASP.NET website I migrated/converted from classic asp to v4.0 There is a 3rd party DLL which is used and I need to register it using regsvr32.

Now all of this works just fine on my local dev environment but also on a test webserver. My environment runs WS2008R2 Enterprise + all updates and iIS 7.5 The test environment using WS2008R2 Std + all updates and IIS 7.5

I have created several virtual machines with a plain environment to test deployment and that works fine.

The live one however causes a problem. That is running WS2008 Std + updates and IIS 7.0.

When getting to the page in question, I get a runtime error and NO idea where to go about this:
Unable to cast COM object of type 'TAMOnlineUtils.clsMainClass' to interface type 'TAMOnlineUtils._clsMain'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{B0B5FC90-90A9-4DD9-A4C6-D779C905B322}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).
at System.StubHelpers.StubHelpers.GetCOMIPFromRCW(Object objSrc, IntPtr pCPCMD, Boolean& pfNeedsRelease)
at TAMOnlineUtils.clsMainClass.GetCertFileList(Object& sPath)
at TAMOnlineWebsite.Report.CalDisplay.DoDisplayCertAndData()
Any ideas anyone? Completely stumped.

I haven't used COM objects in asp.net but when ever I get errors I can't resolve Google the msg usually turns up people who have run into the same problem.

I'd google : No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)). Hopefully you turn up a solution :)

believe me, ive googled and nothing came up.
I eventually solved it. There was a culprit of the DLL but an older version in C:\windows\system32. After unregistering it and deleting it from the folder, all worked just fine.