The Microsoft Snapshot viewer, which is part of all versions of Microsoft Access except Access 2007, has a vulnerability that is being actively exploited by rouge web pages (or web pages that were not secure to begin with). The vulnerability allows the attacker to run a program on your computer, like a keystroke logger, or other ‘bot’ software that gives the attacker full control of your computer.
More information here at the Internet Storm Center http://isc.sans.org/diary.html?storyid=4672 . Microsoft’s advisory is here http://www.microsoft.com/TechNet/security/advisory/955179.mspx
Be careful out there!