|Wow, that lot makes interesting reading and casts a different light on what appeared to be a typical login issue.|
In general it makes me think that the Windows install didn't go very well (as you still had problems afterwards), so using System Restore to go back to Monday will not help much. Of-course you could have a hardware issue of some sort (although there is no real evidence), in which case fixing Windows will not help.
I still have difficulties imagining login issues being due to Windows but I can now see why you are thinking this.
First of all (important), if you see that blue screen again let us have the "error numbers" and if a file is mentioned let us know that as well. There is a good chance that this information will give us a lead to what is going on.
Right now, lets have one last stab at the cookies issue in Firefox. Follow everything on the link below and see what happens to your problem website:
You will be familiar with most of it by now.
I don't know exactly what procedure you used to re-install Windows from the flash drive but if the login issues remain (after above) then presumably there is nothing lost by re-installing again and hoping it goes better this time.
Please watch out for that blue screen info - it could help a lot if we have it.
Always pop back and let us know the outcome - thanks