Following this issue, we have all our important data backed up now. I also bought and installed a new replacement hard disk (WD 160GB PATA) as secondary (slave) drive. I created two primary NTFS partitions on it: a 40 GB system partition, and a 110GB data partition. In theory I could start reinstalling WinXP from scratch on the new system partition, then copying over all user data from the old drive to the new data partition. Once this is done, I could even throw away the old drive, or keep it just to see what happens.

(Note: I don't want to clone the whole drive as it contains a dual boot setup with an old Linux installation which I don't need anymore, and anyway, a fresh reinstall would do WinXP good to get rid of many years' clutter.)

However, I am lazy :-) The old HD is still functioning, the problem has not manifested again since. So I feel there is no need to hurry with a complete OS reinstall.

What I don't know though is whether I will be able to install WinXP on the new system partition at a later stage without affecting the contents of the data partition on the same drive. If this is possible, I can just move over all our data to the new data partition to have it safe, then continue running WinXP from the old drive as long as it works.

Does anyone see any problems/risks with this plan?