Sorry that I've been away. A myriad of things have come up.
Have you been able to disable MSE yet? If not, maybe this video will help. The Disable part is around 4:30 into the video.
A lot of what you describe I think goes back to disk errors and the fact that the machine and disk are quite old. As I'm sure you know, XP is out of support at this point, so it might be time to consider a new machine. Certainly your choice, but honestly you have limited options at this point.
To the extent you can, you should back up all of your user files, applications, email, bookmarks, etc.
Let me know if the video helps