Avast Free update killed Internet connection

[REDACTED]

1st post!
A few months ago I attempted to upgrade the Free AV and, if I recall correctly, it hung and sort of froze. I could not get anything to work properly so attempted to uninstall Avast in order to reinstall cleanly - big mistake. Upon 'successful' removal, I had no Internet connection in any browser. After a few attempts to sort it out, I started using my laptop instead....
My desktop is an older one running Win XP. I just spent a few hours on it and managed to get a solid Internet connection (lots of packets in both directions) but still no browsers. Ping test to 8.8.8.8 (Google) returned with good results. Pinging with page names is unsuccessful. I am a novice at troubleshooting my PC but got at least that far. ipconfig /flushdns did little.
Suggestions?

[Pondus]

See instructions here  https://forum.avast.com/index.php?topic=53253.0
scroll down to Farbar Recovery Scan Tool ...... run as instructed and attach the two diagnostic logs

You may need to download on another computer and transfer frst and logs using a usb stick

[Eddy]

Did you use the uninstall tool ?

[REDACTED]

Ok, Here it is. There seems to be a fair bit of info, I think I will leave it to the experts to decode.
I did try an uninstall with the Avast tool, but it did not repair it.

[Eddy]

Your first problem is that you don't have SP3 installed and the (security) updates released after that.
Fix that first.

[REDACTED]

Have attempted Service Pack 3 installation many times - for some reason it always fails.

[schmidthouse]

Have attempted Service Pack 3 installation many times - for some reason it always fails.

Have you tried installing the Service Pack (stand alone) download from MS in 'SafeMode'?

[Eddy]

What is the exact error you are getting when trying to install SP3?

The download for SP3:
http://www.microsoft.com/en-us/download/details.aspx?id=24

The download for SP4:
Note that this is not a official release from Microsoft, but put together by devellopers.
It basicly is SP3 + many (security) updates/fixes released after SP3.
http://www.softpedia.com/get/Others/Signatures-Updates/Windows-XP-SP4-Unofficial.shtml

[Pondus]

Ok, Here it is. There seems to be a fair bit of info, I think I will leave it to the experts to decode.
I did try an uninstall with the Avast tool, but it did not repair it.

you have attached wrong log .... we want frst.txt and additional.txt

[REDACTED]

"What is the exact error you are getting when trying to install SP3?"

I don't know. I just tried installing SP4 (on your recommendation, thank you) but it still failed. It got most of the way through, then a message about 'access denied', and' installation failed' and' XP may not work properly'. I have tried fixing it in the past to no avail.