All, This is the last for now. Since rebuilding, I have been getting a regular pop up window saying - Messenger service Message from local system to user on date and time. Critical error message - registry damaged and corrupted. To fix this error: Open internet explorer and type: www/registerycleanup.com Once you open the web page, close this window. After you install the clean up program you will not receive any more reminders or pop ups like this. Visit www/registerycleanups.com immediately. OK End of window. I know this is almost certainly malicious, so have been closing the window each time it appears with alt f4. But how do I stop it coming back? Since rebuilding, I have been running Norton Internet Security, and it is fully updated. Again, any help will be welcomed. Many thanks, Ken