I've seen many threads with a similar issue, but no real resolution. The same problem just recently started happening on my X200 running Windows 7 x64 after updating the Intel Wireless LAN drivers. Whenever I would choose Sleep or Hibernate, the screen would shut off and the laptop would stay on for about 10 minutes before shutting down. Upon startup I would get be prompted to use Safe Mode and then get the "unexpected error" dialog from Windows.
After uninstalling the wi-fi drivers, I was able to use sleep/hibernate again.
I tried installing the oldest available drivers (13.0.0), but they still cause the crashes.
How can I get a hold of the 12.x drivers? Does anyone from Lenovo know why the wi-fi drivers cause this?