why has vista stopped automatic updates?

Well Karen,  so, in my case with the error message, I don't think it ran. ...OUgrad

So, this was July KB890830 for Windows Server 2008, downloaded from the Microsoft Catalog, that you ran?   

If so, what I read from your remarks is that the KB890830 executed and extracted mrt.exe (v5.50), saving it as C:\Windows\System32\mrt.exe , but mrt.exe did not run/did not run to completion, based on the info from the Task Manager as this all unfolded, right?

Why did you restore to your previous condition?  If it didn't run or didn't run to completion, then things should be the same as before (without restoring), right??  Granted, you have the new mrt.exe saved on your system, but the one you had before that one  ( mrt.exe Version 5.47.13703.0, April, 2017) had already done its job 3 months ago and is out of date now anyway. 

Just trying to figure out the rationale and learn something more (because I didn't set a restore point when I was trying to run v5.50) and even if I had, after I tried to run v5.50, I set a restore point before installing May WS 2008 patches, set another restore point before running June WS 2008 patches and set another restore point before running July WS 2008 patches.  Those May, June and July WS 2008 patches all ran OK on my Vista x86 and I wouldn't want to restore to the point before I ran v5.50 because I would lose all of those patches and would have to re-do them!

Well Karen, there is no internal mrt.log or other internal File created with execute per 7-Zip. I tried both July x64 versions, the delta (smaller) and the larger version. When I ran the delta, there was no activity with Task Manager. When I ran the larger version, it did appear in Task Manager for about one minute, then an error message appeared saying "This operating system is not supported by the Microsoft Malicious Software Removal Tool". However, it did replace my April System32 Version of mrt.exe with Version 5.50.14000.0. So, in my case with the error message, I don't think it ran. I'll run System Restore to return to my previous condition. An interesting experiment at least...OUgrad

I'll try the MSRT manual download tomorrow. If it updates in System32, I'll copy the File, use 7-Zip to extract the File copy contents and see if there is an internal log File about installing as well as my April 14 Version first. The normal mrt.log File may no longer be linked in Vista.

EDIT - Another thing I'll do tomorrow is open Task Manager to show all Processes so I can watch how long MSRT Runs - probably 5-10 minutes before it disappears from the list. Clicking Image Name in Processes alphabetizes the Processes (ascending or descending) so they don't jump around - easier to watch.

Just to clarify, I got the C:\Windows/System32/mrt.exe that i last executed (v5.50) from the Microsoft Update Catalog (KB890830), i.e., the one listed for Windows Server 2008,  executing it on my Vista x86.  The 32-bit one that is available via the Microsoft Download Center gave me a N/A, if I recall.  

I am curious to hear about the file contents regarding a internal mrt.log and what you see via the Task Manager.

Yes Karen, the mrt.exe File is compressed in every Windows Version, likely because of its' large size. I can't imagine that File being updated in System32 unless it executed. Perhaps someone else can verify. Agree that the mrt.exe File Version also confirms it is current. The last time I ran mrt.exe was April 14. That Version is 5.47.13703.0 from the Details Tab in File Properties. I just got three Microsoft Office 2007 Updates when I ran WU manually, Office Suites, Excel and Compatibility, nothing else. I'll try the MSRT manual download tomorrow. If it updates in System32, I'll copy the File, use 7-Zip to extract the File copy contents and see if there is an internal log File about installing as well as my April 14 Version first. The normal mrt.log File may no longer be linked in Vista.

EDIT - Another thing I'll do tomorrow is open Task Manager to show all Processes so I can watch how long MSRT Runs - probably 5-10 minutes before it disappears from the list. Clicking Image Name in Processes alphabetizes the Processes (ascending or descending) so they don't jump around - easier to watch.