How to disable RC4 in Windows 2012

On the suggestion of checking the Power Management settings by @joeqwerty I created a new Power Plan with the following settings:

• Display -> Turn off display after -> On battery (minutes): 0
• Display -> Turn off display after -> Plugged in (minutes): 0

I set this as the active power plan, and applied the GPO. After 25 minutes the machines are no longer automatically locking.

Here are the full steps for creating this:

1. In Group Policy Management Editor, edit the target GPO
2. Go to Computer Configuration\Preferences\Control Panel Settings\Power Options
3. In the right pane, right click and select New -> Power Plan (At least Windows 7)
4. In the Advanced settings tab, select the Create action
5. Enter a new plan name (e.g. "Don't lock")
6. Select Set as the active power plan
7. Expand Display -> Turn off display after
8. Change On battery (minutes) to 0
9. Change Plugged in (minutes) to 0
10. Click Apply, OK
11. Apply the GPO to the target machine(s)

TL;DR:

Clear your C:\Windows\Temp directory and other Temp directories for good-measure - then it should install updates fine.

Explanation:

As this is an Azure VM, Microsoft's "Basic" support tier is available - granted it took 3 days to arrange a phone-call, but the support staff were able to find a workaround just today.

In the CBS.log file he spotted this line (trimmed and tidied-up by me):

2016-08-16 20:26:50, Error                 CSI    00000006@2016/8/16:20:26:50.808 (F) CMIADAPTER: Inner Error Message from AI HRESULT = 8004402f [Error,Facility=FACILITY_ITF,Code=16431 (0x402f)]
[
[210]"Parsing MOF file: C:\Windows\system32\wbem\NetTCPIP.mof
Error 80 in Function CMofLexer::CMofLexer line 614
C:\Windows\system32\wbem\NetTCPIP.mof (1): error SYNTAX 0X8004402f: Error creating temporary file"
]
[gle=0x80004005]

The important bit being this error:

Error creating temporary file

He instructed me to change the default environment-variables: TEMP and TMP in both System and User definitions to C:\TEMP and to ensure Everyone had Full Access to C:\TEMP.

After rebooting the clogged-up updates installed without any further issues.

After installing those updates fine I then deleted all of the files in the original C:\Windows\Temp directory (which took 5+ minutes, there were a lot of deeply nested files). I then reset the TMP and TEMP environment variables back to C:\Windows\Temp and rebooted.

Two new updates were then ready to install and installation completed without any problems.

So I think the problem was bad data in the Temp directory that prevented the updates from doing anything.

Update in Mid-2017: I had a similar incident on a Windows 10 laptop recently with the same error code. I immediately went to the C:\Windows\Temp directory and saw it had a lot files in it (about 16,000 files and folders), including deeply-nested folders too. After I deleted everything in the directory and rebooted I was able to install the updates again.