I have a Samsung NC-10 netbook with a fresh install of Windows 7 Home Premium 32-bit (it only had 2GB).

If Microsoft .NET Framework 4 Client Profile is installed on it, Windows Update will always return error code 8024402F ("Windows Update encountered an unknown error").

As soon as I uninstall it, Windows Update works just fine again. Out of the four computers in this house, only this netbook has the problem.

My question is: How can I get the .NET Framework 4 Client Profile installed on my netbook and continue to have a functioning Windows Update?

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The hard-drive recently died on my netbook so I replaced it with a nice new SSD and did a fresh installation of Windows 7 Home Premium (SP1) - along with all the updates.

At some point I found that, when I ran Windows Update, I was greeted with error code 8024402F ("Windows Update encountered an unknown error").

Looking in C:\Windows\WindowsUpdate.log, I saw the following issue:

WARNING: ECP: Failed to validate cab file digest downloaded from http://download.windowsupdate.com/msdownload/update/software/dflt/2012/02/4913552_4a5c9563d1f58c77f30d0d5c9999e4b8bff3ab21.cab with error 0x80091007
WARNING: ECP: This roundtrip contained some optimized updates which failed. New Update count = 0, Old Count = 3
FATAL: ProcessCoreMetadata did not return any update to be committed
WARNING: Sync of Updates: 0x8024402f
WARNING: SyncServerUpdatesInternal failed: 0x8024402f

When I downloaded the CAB from the URL listed and opened it, it contained a file called 4913552.txt. A search on Google suggested that it's related to Microsoft .NET Framework 4 Client Profile. Other people had reported problems with it breaking Windows Update, but they were running Windows XP.

I tried the steps outlined on the Microsoft site for this error code, but it reported that there was nothing wrong.

I also found this superuser question, I tried all the answers listed but none of them made any difference. My router doesn't block ActiveX, changing my internet settings in IE made no difference, assuming it was a corrupted update repository didn't do anything (except wipe my update history), my date and time was correct, switching to Google's DNS didn't work and neither did disabling IPv6.

Figuring that this update was corrupted, I repaired it and nothing changed. In desperation I un-installed it and Windows Update started working again!

Brilliant!

I then downloaded the full version from the Microsoft website, installed it and, thankfully, Windows Update continued to work just fine.

A week later I turn on my netbook and Windows Update is broken again with exactly the same error message and log entries as before. Repairing .NET Framework 4 Client Profile did nothing, removing it entirely solved the problem again.

Thinking this might be some odd Windows installation issue, I formatted the hard-drive and re-installed Windows. Same problem as before - as soon as .NET Framework 4 Client Profile ended up on the netbook, Windows Update stopped working and reported error 8024402F. As soon as it was un-installed, everything worked just fine again.

There are three other machines in this house and all of them have working Windows Update and this Client Profile. Does anyone know why it causes this netbook to break and, more importantly, how I can fix it?