error 80070026 (unknown) when installing .net framework 3.5 sp

I'm running Vista Ultimate on a dell XPS laptop. Most updates are successful.
I previously had this prblem trying to install Tinker. I got support from
microsoft, but they couldn't figure out what was wrong. They finally
suggested reinstalling Vista, but as everything else is working, I chose not
to do it. I have a similar configuration on my desktop and have no problems.
So, I am thinking it must be some hardware-related driver.

Does anyone have any ideas how to resolve this?

I encounter the exactly same problem with a Dell XPS M1330 and Vista. Don't know whether it's important to download this update. All other updates install ok. Any adivce?

0x80070026 ERROR_HANDLE_EOF
Reached the end of the file.

Suggest you manualy download the full package and *save* it:
http://download.microsoft.com/downlo...dotnetfx35.exe

Once the download completes, Clean boot Vista.
Do "Step 1: Perform a clean boot"
http://support.microsoft.com/kb/929135

When the system is clean booted, then attempt to install dotnetfx35.exe
by *right* clicking it, choose 'Run as administrator', follow the
prompts to allow it to run.
Restart the system IF it installs. A successful installation would
indicate that 3rd party software had previously interfered with the SP's
installation.
*REMEMBER* to go back and undo the changes you made in order to Clean boot.


If it fails to install again, check the installation logs to see where
it's failing. See the ".NET Framework 3.5 and 3.5 SP1 setup log files"
section here to find out where they are located on your system:
http://blogs.msdn.com/astebner/archi...0/8445569.aspx