First of all you can not upgrade your os directly from XP to windows 8.1. you can only install a fresh os. But your machine should be compatible with 64 bit. If you have not then you need to get a new machine.
you need to check your all connections between your computer and cpu. if connection are ok then you need to use an other lcd or monitor to check your display. once you will do that then you need to clean your ram and motherboard.
I seems like you have added or remove any program on your computer and that's why your dll file got currupted. so in this situation you need to go ahead and restart your computer in safe mode. and then you need to run "sfc /scannow". once you will run and then you need to restart your computer. now it should start working fine.