Can I check in Active Directory to see who has logged to a machine in recently? The machine in question is joined to the domain. The problem is that it's also protected using DeepFreeze, and therefore any history on the machine itself is wiped during it's nightly reboot.
The closest you'll get is by examining the Domain Controller security logs as they record the logins by the user and workstation itself. If those have scrolled off the Security log, you're pretty much out of luck. This is how companies like Splunk make their money.