Adobe have released a minor upgrade to Adobe Reader
Adobe Reader 8.1.1 update for Windows
What’s new in 8.1.1
• Close a potential security vulnerability on Windows® XP computers that have Internet Explorer 7 installed. See the Adobe Security Bulletin (APSB07-18) concerning this issue
• Address several PDF forms-related issues
• Provide additional stability
The update file is about 6.3Mb, the full file about 22Mb
For those with Adobe Acrobat 8.1, it has also been updated to 8.1.1
Adobe Acrobat 8.1.1 Professional and Standard update for Windows