Are you using Internet Explorer 8? If so, you need to read on.
A recent zero-day exploit being actively used in the wild and was likely the cause of a watering-hole attack that was launched from the US Department of Labor.
To help IE8 users mitigate any further exposure to attacks from this flaw, Microsoft released a quick fix solution to address the exploit.
Microsoft is still working on a complete fix for the exploit. In the interim, if you're using IE8, click here to head to Microsoft's website and scroll down to the Fix-It icon labelled "Enable".
If you'd like to read more, Cisco Systems has a good analysis of the watering hole attack.