HP Procurve 4000 auto reboot?

[kastkc]

Hello I was logged in to a 4000M via telnet over wireless. I was right near the switch. I had just added vlans and it asked me if I wanted to reboot. I declined. I set my laptop down it went in to power save and the next thing I know the switch went offline. I had to physically reboot it in order to be able to consle back into it via console cable. Any suggestions as to what would cause this? Is this common? Thanks you.