I must've done the upgrade to IE11 several dozen times, most recently a couple of months ago when I installed Windows 7 on an SSD. I've never run into problems like you describe, so all I could say would be that something in your system has gotten messed up. Since you don't know what that is, I think the advice to reinstall is good advice. When I've reinstalled Windows 7, I've used Windows update, but only installed 50 or so of the updates at a time. If you try to install them all at once, it will grind away for a while, then bomb out, possibly with something getting screwed up.
Several months ago I had a problem with I.E 9 I decided to upgrade to IE 10 , bad move screen locked up, could not get IE 10 to open, well the screen was open but no address bar or anything else.
So I did system restore and went back to IE 9
I kept on getting messages "you are using an outdated version etc. etc ."
So today I went to MSN and downloaded IE 11 to be told me it had downloaded but in "About Internet Explorer" it tells me it is still IE 9
MSN help line are telling me because I built this machine they can't help me.
They told me to re-install Windows 7 again.
All I want is IE 11 running good.
The question is as follows;
"What do I need to undertake to get IE 11 up and running"
Lastly all my updates are up to date.