Blue screen of death following virus scan

Stephen, In future please refrain from carrying out multiple topic postings on the same subject! You won't obtain an answer to your query any faster!. Also please try to keep the whole conversation in one question/thread to speed up any resolution. Please see your other posting (https://support.avg.com/answers?id=906b0000000Db16AAC).
AVG Guru

Booted an old XP computer today that had AVG 2012 Free installed. Updated the anti-virus definitions and completed a system scan. At the end of the scan, AVG prompted for a system restart. When attempting to reboot, the following error appears: "c000021a {Fatal System Error} The session Manager Initialization system process terminated unexpectedly with the status of 0xc000026c (0x00000000 0x00000000). The system has been shut down." I'm assuming that AVG quarantined a needed system file. How do I regain access to my computer?

Thanks for your help!
Stephen, In future please refrain from carrying out multiple topic postings on the same subject! You won't obtain an answer to your query any faster!. Also please try to keep the whole conversation in one question/thread to speed up any resolution. Please see your other posting (https://support.avg.com/answers?id=906b0000000Db16AAC).
AVG Guru