Windows 7,find who accessed my computer on network?

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http://serverfault.com – It seems something tried to delete root c:/ folders on my computer and it did started delete process alphabetical order. Not sure what is cause. any known virus? We have company network edition of antivirus running, and full scan did not found any virus activity. That makes me suspious about someone on company network attempt to delete? can this possible? If it is how do we know from windows server that who accessed my computer over network? (HowTos)