Unable to install Microsoft .NET Framework 4.0

hullo

I've been running a computer on Windows Vista SP2 for about two and a half years now, and I believe something's gone horribly wrong. I was downloading a game which required the .NET framework, so long story short I tried to manually install the .NET framework 4 and all the installer would tell me is that 'no such interface is supported'.

I am not that tech-savvy, but I believe it has something to do with my Windows Updater, which cannot update itself anymore as the windows update service itself is not running. Thinking it was some sort of virus in my kernel, I did a full scan with Microsoft's Malicious Software Removal Tool in safe mode and I didn't find any viruses that could be causing that, so I have no idea why it's gone kaput. again though, this could be totally unrelated to my framework installation problem.
Any help with it would be appreciated.

(crossposting from cnet)
 
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