If you have the XP CD, put in in the drive -Wait for autoboot and exit-.
From run type in 'sfc /scannow' (Without the ' marks-- Don't forget te space between sfc and /)
This will check your system for any start up errors and reload from the CD if required.
It is always advisable to store any email program to a seperate drive as this may have it's settings changed.
To store email (Outloook Express).
Create a folder on your hard drive called (e.g. email saved).
Highlight the email you want to keep, and drag & drop to the new folder. You now have a pernament copy of the emails.
If all goes well and you do not need a copy of your emails- just delete them like any other file.