As a user who does not hesitate to recommend Avast, all I can say is sorry, but without any authority.
This was caused (apparently) by a corrupt VPS update, which appears to have now been put right. This is one of only two posts I have been able to make to the forum, I reckon because the forum servers were overwhelmed by demand from users such as yourself.
Since you have restored the original factory settings, I don't know if it is possible to restore your computer to its prior state. Maybe try system restore? Perhaps someone who knows more about OEM machines will know how to do this. (I've never used on. I have a desktop, and installation disks for all software, including the OS.)
I think that restoring to factory settings may have deleted everything and every file you have placed on the hard drive since you've had it. If there is a chance of restoring any of these files, (that's assuming a system restore does not work) it would be helped by not using the computer, so that any files that re recoverable are not over-written.
One thing about restoring it to the factory condition, is that there is likely to be a trial version (probably of Norton) still present. The latest version of the Norton Removal Tool (for use after using add/remove programs>uninstall) can be found
here. All the AV's have their hiccups from time to time.(AVG had a lot of seriously disgruntled users when they brought out version 8. Norton, about a year ago, released an update that prevented users of Chinese-language OS from booting. Given that a fair percentage of the Windows installations in China at the time were probably pirated, that definitely raised the eyebrows of the conspiracy theorists.)
This appears to have been a rather large hiccup - it's all over the web. It certainly is not going to stop me from using Avast, but I am fairly interested to know what caused this glitch.
I don't know how many other AV companies have good phone support, for cases like this. Quite likely, if you'd had an AV with a support line available, you probably wouldn't have been able to get through, anyway.