Can no longer login to CPanel since new computer with Vista.

Firefox works fine on Vista

 

Allow your browser to accept cookies

 

IE7 works fine (normally) on vista.

I don't have Nortons, but if you've disabled it and still receiving the error I would suggest the following from IE;

Tools -> Internet Options -> Security
Select Internet, Click Default
Select Local Internet, Click Default
Select Trusted Sites, Click Default
Select Restricted Sites, Click Default.

Select the tab Privacy, Click Default (will fix cookie permissions as jayh38 suggests)

I know norton's like to change these options on your behalf to "help" you with security (aka, muck everything up).

If this doesnt' help, my only other suggestion is to (in that same window) Select the tab Advanced and "Restore Advanced Settings" (maybe even "Reset Internet Explorer settings" found on that bottom of that page) Again, Norton's loves to go overkill and _will_ change settings such as these. For this reason I've never suggested Nortons to my clients.

Let me know if any of that helps your problem.