SURPRISE WINDOWS 7 UPDATE?

Perhaps you can Restore it back to an earlier Date and get a clue there of whatever happened and did the changes for you? Also, you could look in the Update History to see what the latest one rated as Important was. I'm also running Windows 7 and mine was on 11/12.

There is a chance you've got the update for IE 11 installed, which explains why your Chrome has been hijacked. That was a rolling update. I actually downloaded it directly just because even if I don't use it directly, I do use it to switch rendering engines from Firefox to IE when the webpages don't work as they should (a bit too often!).

It DOES sound like you were logged into a brand new user profile though! You should check to see if there is another user in the Users folder. This happened to me once... though I can't remember the specifics. (iirc, it was because I logged in directly to the PC once after having the harddrive encrypted, instead of logging into the domain. It was a work laptop. Also also, encrypting a harddrive is annoying as fuck and prone to crashes/irrecoverable states)

author=Sam
Just checked that and What's weird is that it shows me as being logged in as me, but all the My Documents, My Music etc shortcuts are listed under C:\User\TEMP so you may well have sussed it.

Booting the user to a temp profile is actually a common virus trick. It will sometimes seem like it's fixed and then come back again later. If you have an antivirus program, reboot your computer into safe mode by pressing F8 as it's starting up (choose Safe Mode with Networking), and run a virus scan from safe mode. If you don't have an antivirus program, download Malwarebytes and run a scan with that from safe mode - you have to pay to get the constant background protection with Malwarebytes, but running manual scans is free.

Source: I work at a computer repair shop and fixing viruses is what I do all day. I've run into this one twenty or thirty times.

Don't let the name fool you. If you run it in safe mode, it does a better job of detecting and removing viruses than most antivirus software. It just doesn't hook into every action your system does, like a full security suite would, so you do have to run it in safe mode to get the full benefit. Though this also means it doesn't slow down your computer like antivirus programs.

Avast is shitty; get Microsoft Security Essentials alongside of Malwarebytes if you want something decent.

Too many antivirus programs is often worse than none at all, though. Malwarebytes plus one other thing is plenty. More than that and they're just going to interfere with each-other and keep your computer from working correctly.