Hi, Carrie.
In IE, go to Tools / Internet Options / Advanced.
Click on the reset to default button near the bottom of the advanced tab.
Close IE.
Try to proceed with the purchase from within OneCare again.
If you still get the error, try the following:
Close OneCare (just the main screen and any open windows).
Open IE.
Go to
http://onecare.live.com Click on the buy today button
It should forward you to a page where you will sign in and proceed with a purchase.
Once purchase has been confirmed, open OneCare, click subscribe and sign in with the *same* LiveID you used during the purchase.
If that still doesn't work, please review the information on the KB article referenced here:
http://social.microsoft.com/forums/en-US/onecareinstallandactivate/thread/ba26b781-da18-4ce4-be8c-22647bd5d8fc/And feel free to contact support at any point.
How to reach support (FAQ) - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
One other note, you can save some money by purchasing a retail copy of OneCare from a store or online retailer. All you need is the PIN or Key from inside the package. You can then start your subscription by signing in with your LiveID and choosing to activate with a PIN or Key, but if you are encountering a script error for IE, you may need to get some help with IE before proceeding:
Internet Explorer 7 Solution Center
-steve
Microsoft MVP Windows Live / Windows Live OneCare & Live Mesh Forum Moderator