I tried all the suggestions - rsetting IE, C Cleaner, etc., without any joy. Rolled back to a System Restore BEFORE installing the Live ToolBar - and IE7 was still unable to open any pages!!
So I re-installed IE7 (the installation program automatically clears the old version) and I now have a working IE7 again.
Many thanks to all for trying to help.
Before I mark this RESOLVED, can I ask advice. Is IE7 a better/safer brwser than Firefox. Is it worth attempting to add the Live Toolbar, and if so will that affect the the answer to the previous question?