I've forgotten almost everything I dvds knew about the command line and couldn't work out what was wrong with Windows this morning. In the end I created a second version of xp which I boot instead of the shafted one. On the plus side I didn't delete all the stuff I've done since the last backup.
Time was I might have known what had gone wrong and not had to resort to the dodgy and slapdash solution I employed. I'm not handing in my geek card, there are still many ways in which I'm qualified, but I have forgotten some of the basic skills.