Laptop shuts down while in sleep mode

I have recently purchased an HP ENVY 15t-j100 Quad Edition CTO Notebook Windows 7 Professional (PC Product #: E1P05AV). I'll usually close the lid to put it into sleep mode when I have to do something else. But when I open it back up, it has the "Start windows normally or safe mode" sreen. I've noticed that this only happens after a certain amount of time of being in sleep mode. If I wake it up prior to that, it works just fine. I hope that this can be resolved since this is a brand new laptop.