I have an easier solution. In Windows Update, right-click on each update & select the Hide option. Then it doesn't bug you any more.
I know, I know, that's just asking for trouble. Well, I'm rather annoyed that I'm seeing this problem with:
(1) Security Update for Microsoft .NET Framework 4 on XP, Server 2003, Vista, Windows 7, Server 2008, Server 2008 R2 for x64 (KB2656368)
(2) Security Update for Microsoft .NET Framework 4 on XP, Server 2003, Vista, Windows 7, Server 2008, Server 2008 R2 for x64 (KB2686827)
(3) Update for Microsoft .NET Framework 4 on Windows XP, Windows Server 2003, Windows Vista, Windows 7, Windows Server 2008, Windows Server 2008 R2 for x64-based Systems (KB2468871)
My system (click the My System Specs button on any of my posts) is barely a couple of weeks old. A buddy of mine gave me -- I say, donated, free, gratis, it's good to have friends like that -- gave me this system & he installed the OS for me. I've just tweaked some of the cosmetic stuff within the system, customizing it very lightly. As far as I can tell, I have no applications that actually use .NET. Task Manager never shows any of those mscor* tasks running except after I've tried to install the above 3 mentioned updates. It is also annoying that when Windows Update does launch those .NET services as part of the update process, I have to go into Services and manually demote their Startup Type back to Manual when I also stop them.
My point is, this is a pretty fresh install. The only application I have ever encountered that explicitly required .NET (and specifically for which I installed .NET, which I did not have prior to that) was one to update the BIOS in my portable XM radio receiver. I ran that exactly one time about a year ago on my previous system (it was WXP) & never saw the mscor* things in Task Manager again after that. And I've never (2-3 weeks of usage) seen them here on W7 except, like I say, when I have been trying unsuccessfully to get these updates installed. I have not installed the XM radio app on W7 & don't foresee installing it unless XM comes up with some really really really compelling feature update to the radio. I'm not sure why my buddy included .NET in this install, but he did & you know how you're supposed to treat gift horses . . .
<<<Total sidetrack. When I composed this post, I wrote the letter W and the digit 7 side by side. Apparently, this web site promotes that abbreviation to the full wording Windows 7. It doesn't do that for WXP or WNT or W98 or W95 or . . . ?>>>
I found advice elsewhere to run sfc /verifyonly & then some string extractor to analyze CBS.log. (I'm thinking CBS doesn't stand for Columbia Broadcasting System here. Check Boot Sequence? Collect Basic Statistics? Cool Beaners, Sam?) The only file it flagged was explorer.exe & I gather from my other reading in these Forums that this is actually something of a false positive due to the fact that I have modified my Start Menu Orb.
I tried using Windows Update to install each update by itself, with intervening reboots. No joy.
There's a couple of other things I checked based on things I've read in these Forums but I don't remember them now & besides, the updates still wouldn't install.
So I don't see why I should troubleshoot something like this. This is practically a virgin install. The problem isn't mine. It's Microsoft's. They need to figure it out. And their advice to me to get these updates installed had better not involve any disabling, uninstalling, or other quasi-violent if not destructive actions on my part. My system is functioning perfectly & since it ain't broke, I ain't gonna break it, let alone try to fix it.
Like I say, none of the .NET executables runs on my system during normal usage. So what's my security exposure? I'm running the Microsoft Security Essentials as well as AVGFree. I'm not too worried. So I've hidden the updates. If Microsoft ever pushes out another .NET update, I will allow Windows Update exactly one chance to install it, and then if it fails like these have, it gets hidden, too. The updates listed above got the 3 strikes you're out treatment. Future updates get only one strike before being sent to the showers.