I understand it's not going to sleep, but have you confirmed you disabled the power settings? Check the bios as well?
1. Click Start, type gpedit.msc and press Enter. 2. Locate Local Computer Policy -> User Configuration -> Administrative Templates -> System -> Power Management. 3. Set the state of “Prompt for password on resume from hibernate / suspend” as “Not Configured”. 4. Open Control Panel -> Power Options -> Require a password on wakeup. Choose Don’t require a password and click Save Changes.
Are you the only user? If not, a group policy could force this.