Tablet PC ghosts

I have an Acer Tablet C300 running XP. Purchased 4 years ago. A month or so ago I had to replace the hinge. Since then I have had these problems: when I close the lid with the computer on, it turns off within a few seconds; whenever I use the pen, i get a quick BSOD, and the computer restarts. At first the pen worked sometimes, but now it always results in a BSOD. I have searched the internet without success, and wondered if anyone has a suggestion.