Errors 80071A91 and 80070643 when installing updates

Hello,
I have an Asus G75V with Windows 7 on it.
For a few weeks now (since mid-April), I've been encountering failures when trying to install the updates offered by Windows Update.
10 important updates have failed with 2 error codes: 80071A91 for some and 80070643 for others.

I've tried everything, the fixes... nothing works.

I found a seemingly similar issue on this forum with the following response:
"
the only method that worked for me resets the Windows Update counters completely (preferably to be done in safe mode):

- disable Windows Update
- delete everything under C:\Windows\SoftwareDistribution
- open a command prompt cmd.exe (or start/search "cmd" / right-click / run as administrator)
- execute the following commands one after the other:

1. fsutil resource setautoreset true c:\

2. cd /d%windir%\system32\config\TXR

3. attrib -r -s -h *

4. del *

- then:

1. cd %windir%\System32\SMI\Store\Machine

2. attrib -a -h -s *.TM*

3. del *.TM*

- NOW REBOOT! (restart)"

BUT on step 4, the deletion does not work with the message "these files are being used by another process."

What should I do?

Thank you very much for your help!