Laptop not booting correctly from sleep/hibernate

I posted here a few months ago and everyone was very helpful, so I thought I would try it again with a new computer and a new problem.

I have a Lenovo ThinkPad w500 running Windows 7 32-bit and every time I wake the computer from sleep, the computer boots up to the desktop, but after a few seconds goes back to sleep. The same phenomenon occurs for hibernate, with the laptop going back to hibernate. This happens exactly once, meaning if I try a second time to resume from hibernate or sleep, the computer boots normally. This occurs regardless of whether the laptop is plugged in or on battery power.

Shut down and restart are normal. The only other thing I have noticed about this problem is that when I wake up the computer from sleep, before it goes back to sleep, the "Safe to Remove" bubble appears on the desktop telling me I can safely eject my CD/DVD drive.

I have tried disabling / re-enabling hibernate from the command prompt but it did not fix the problem.