Windows 7 - Window 7 update on Nov 12 made computer very slow

This is a bit similar to 'made my pc laggy' thread' except I'm still at the laggy stage rather than the complete failyre that Karen's attemp to fix progressed to. Here's what happened:

Did update
Got balck screen with cursor for ages once update complete, eventually made it through to windows but everything loads glacially slowly. Avira antivirus turned itself off.
Uninstalled the Nov 12 update.
Still very slow. Safe mode works but avira problems persist

I have no system retore points.

Anyone have any suggestions that dont imply a full system restore?

Thanks

Immediate thought is malware or system file corruption.

Note that the system can be slow after .NET updates for a while, as it re-optimises (whatever that means!) the installation. Once that's complete (I generally leave the system alone for an hour or so) it's back to normal.

Is it any quicker in Safe Mode?
Uninstall Avast, and run their cleanup tool - does that speed things up?
Reinstall Avast - does that slow things down again?

I would suggest running CHKDSK and SFC (assuming that you’ve already tried a System Restore?)

type in the Search box
CMD.EXE
right-click on the only file that is found
Select Run as Administrator
- the Elevated Command Prompt window should pop up
At the Command prompt, type
CHKDSK C: /R
and hit the Enter key
You will be told that the drive is locked, and the CHKDSK will run at he next boot - hit the Y key, and then reboot. The chkdsk will take a few hours depending on the size of the drive, so be patient!

After the CHKDSK has run, Windows should boot normally (possibly after a second auto-reboot) - then run the SFC

SFC -System File Checker - Instructions
Click on the Start button
type in the Search box
CMD.EXE
right-click on the only file that is found
Select Run as Administrator
- the Elevated Command Prompt window should pop up
At the Command prompt, type

SFC /SCANNOW

and hit the Enter key
Wait for the scan to finish - make a note of any error messages - and then reboot.


Try using Malwarebytes Anti-Malware to clean the system.
Download and install Malwarebytes Anti-Malware (www.malwarebytes.org ). Update it, but do NOT accept the offer of Real-Time protection (it may cause problems).
Run a Full System Scan in your main user account, and Quick scans in any other account.
Delete everything it finds. You may well find that Avast complains a few times during the process – allow that to do its thing at the same time.

In safe mode it works ok though avira antivirus doesnt load and has turned itself off i think. Malwarebytes shows no probs on quick scan but crashes on full scan

Was that running MBAM in safe mode? - if not, try it there.
If Avast is turned off in Normal Mode, then you have a major problem.
Have you run teh CHKDSK and SFC? What results?

Which updates were installed on the 12th? - list all, including any failures - check the Updates history in Wndows Updates.

chkdsk is running now, looks like it will take a while, as you said.

Malwarebytes only running in safe mode.

In normal mode avira (not avast) antivirus opens but shows that main antivirus has turned off

By major problem do you mean virus/malware? If it is that, why would it only have manifested during a windows update? Never hyad any problems with my laptop until that pesky update

Windows updates change system files (by definition) - Malware can also change system files (that's their main purpose in life).
Malware can also disable anti-malware apps (again - it's part of their purpose)
Sometimes, updating System files with approved files will expose malware in such a way that it suddenly becomes visible to anti-viruses, or can break it in other ways.

There is NO perfect solution to malware - except not allowing it onto your system in the first place. That means that you have to have a healthy degree of paranoia when you access external systems such as the internet, or even your friend's network.

From what you've told us, it seems to me that the probability is that you have an infection of some kind (I may well be wrong, as I'm not as up-to-date as I used to be) - and need to address that beofre attempting to solve anything else.