Starting today when I click on a link in an email, at least the HTML ones, I get a note that says that the action has been stopped due to restrictions on my computer and to see my system administrator. Since that is me, I don't know how to fix it. How do I lift these restrictions? Thanks for any help.

This has happened to me also when i installed Firefox. What i had to do was set Firefox as the default browser to open up the links in the e-mails. Before it was IE.
DO THIS:
In Windows XP: Go to Add and Remove Programs, Set Program Access and Defaults. In “Choose a default web browser”, check on the “Internet Explorer” option and click the OK button.

In Vista/7: Access the Default Programs applet from the Start menu or Control panel. Click on the “Set program access and computer defaults” (last option) then expand Custom. In “Choose a default web browser”, check on the “Internet Explorer” option and click the OK button.

In my case it was when Google Chrome was installed because I downloaded some software and wasn't paying attention and it added Chrome. Turns out I had to go to a MS fix it program that reinstalled a registry program and that fixed it. I forgot to post here that I had it fixed. Thanks for responding with your solution. I don't know if that would have worked or not, but I appreciate you taking the time to answer.