Is there an option in Windows that keeps track when your computer was last rebooted?
Just run cmd.exe with this command
systeminfo| find "System Boot Time"
For others solutions go to http://www.walkernews.net/2008/06/18/how-to-check-windows-last-boot-up-time/
It will be in the event logs.
Event Viewer and select the
System log from
Windows Logs in the tree on the left.
There will be a lot of log entries in there, so click
Filter Current Log... on the right and filter it for the
Kernel-General log source only.
You will then find entries saying such things as:
The operating system started at system time 2011-03-09T00:04:30.375199800Z.
The operating system is shutting down at system time 2011-03-09T00:00:10.192212700Z.