Error occurred during install of assembly policy 8.0.microsoft.vc80.CRT

Question

I've been trying to upgrade to itunes 9 on windows vista system. During the install, it says "error occurred during installation of assembly policy 8.0.microsoft.vc80.CRT, version 8.0.50727.403 type win 32 policy public key token=1fc8b3b901e18e3bprocess architecture=x86 Quicktime installs OK, but Itunes install is interruped -- Apple Support install portion is rolled back after this error pops up. I went thru suggested Apple troubleshooting options, got same error. Ran install as administrator from desktop, also did not work. Tried installing both thru apple software updater and directly from Apple website -- still get error. I asked about this on Microsoft site, they sent me back here. thanks for any solutions.

Answer 1

flabud, here are the next steps that I would suggest.
1) If you haven't done so already, reenable McAfee. I'm guessing that you've already done that though.
2) Create a manual restore point. You can also do this after each of the following steps if they are successful but you don't have to necessarily do it each time. One restore point at the beginning should suffice.
3) Disable Windows Defender so that it no longer has possible conflicts with McAfee. McAfee put out this notice earlier this year because the combination of those two programs were causing problems and that notice describes how to disable WD. You should also uncheck Windows Defender using MSConfig (Startup tab) after disabling it as described in the notice. One of my systems had the exact error message described in the notice and since disabling WD it has encountered no further problems.
4) Check Programs and Features in Control Panel for the following programs and install using the associated links if they do not show up. Restart after each installation and then check to make sure the install was successful in Control Panel.
a) Microsoft Visual C++ 2005 Redistributable Package (x86)
b) Microsoft .NET Framework 3.5 (if MS .NET Framework 3.5 SP1 already exists then do not install this)
{I added this because I had problems with this install at the time of the McAfee/WD conflict}
5) Run Windows Update and install any Important or Recommended updates. The installation of the programs in step 4 should allow the others to complete successfully but if any still fail make a note of them as you did before.
6) If everything completes successfully to this point then reattempt the installation of iTunes using the file that you have in the Downloads folder.
I've written the steps in the order that they should be done so if you run into a snag in any step let us know before proceeding to the next step.