Reposting @STEVE ONLY =>
What updates did you install last week?
Possibilities include KB2809289, KB2814124, KB2807986, KB2791765, KB2670838, IE10 plus a few updates for MS Office.
Note: KB2670838 is an IE10 Prerequisite Update. If KB2670838 wasn't already installed, it would have been "drive-by" installed when you installed IE10 (in which case KB2670838 prolly wouldn't be listed in
Installed Updates or Update History.
PS: Was IE10 Release Preview installed? Is Automatic Updates set to the Automatic configuration and if so, was IE10 installed via Automatic Updates?
PPS: What is the full name of your installed anti-virus application or security suite and
when (approx. date) does your current subscription expire? What anti-spyware applications (other than Defender) are installed? What third-party firewall (if any)?