I just did the 10.6.8 update. I'm getting an error An error occurred with an Internet plug-in"

I am trying to prepare to install Mountain Lion. I did the most recent update a few hours ago. Now my MacBook is running very slow & I get an error message "An error occured with an internet plug-in". I can click OK and continue onto the page, but it's every single new page online that I'm getting this error.