This might be very important. I am experiencing exaclty the same on Windows 7 Home 64. I do have a patched version of explorer, I modified it something like 1 year ago, but what it important is that after replacing it with an old backup (I luckily have Ubuntu installed) the system is back working.
I will test it and see if it comes back with the same problem then cases are two:

  1. Everything goes on working as usual - meaning that it was a fp due to the patch or the patch itself did contain a virus which slmehow activated only now or I somehow deleted the virus (I deleted temp and temporary internet files from Ubuntu).

  2. At next reboot I get back to the same - then it means that the infection is not a fp and it is not related with patching.

Anyway it is also worth to mention that yesterday Chrome was reporting me a dangerous download, which actually was not but could potentially be as it contained programs related with bioses which anyway I didn’t open there since were for another laptop. But the point is that this virus has been probably downloaded by some other malware which xould have been there for a long time…