This seemed to be the correct place for this, but let me know if it isn't.
I've a PC I've recently built, and I've gone most of my life with no anti-virus software (though I have a firewall and many malware and maintenance tools), and very rarely have I been infected. It was recently recommended that I install an antivirus and I did. AVG's the one. It came with its tune-up programme as well, which I didn't understand was separate as it's all on the 'dashboard'. This thing has nearly levelled my computer. I've uninstalled it (which was a fight in itself), owing to loads of performance troubles, only to find that despite some message to the contrary it left all its settings intact, and I have no system restore, no lock screen background (though the log-on screen has its one), improper search functions (as in nearly none) in the folders and the start menu, no previews for documents in explorer, and whatever else it's done that I mayn't have discovered. Most of it's probably a result of the Turbo setting I thought I was trying.
I was considering reïnstalling it and trying to undo all this stuff, but I'm a bit afraid of that given what it was doing already and that some people report unusable computers following an installation of it.
0x81000203 is the error code for the system restore. I've already set the volume shadow copy to automatic in Services.msc, and disabled AVG Service in the same (although I did uninstall all AVG software, using AVG's tools as no-thing else would work).
Thanks very much.