Well 0xD1 errors are usually due to a faulty driver but sometimes can be due to faulty or mismatched RAM. In order to help you we need a lot more information from you.
1. Give us your system specs including what OS you are running, what security software tou have installed, the amount of RAM you have and is this a pre-built PC (Dell, HP, etc.) or one that was built by you or a friend?
2. What has been the history leading up to getting this problem and error code? Did you do something different, install or uninstall software, and have you been having issues for a long time or is this recent?
3. When did this error occur? What were tyou doing at the time?