Retina Mac shows gray screen when waking up: what to do besides loosing work?

Question

(see also http://apple.stackexchange.com/questions/96188/retina-mac-shows-gray-screen-when -waking-up )
This is the first time that my Retina MacBook Pro wakes up from sleep with a gray screen. After about 10-20 seconds, the MacBook falls asleep again.
Some points that might be relevant:
The only difference between power adapter and no power adapter is that with power adapter it does not go to sleep again.
The battery is almost full (I closed the lid last night when it was about 90%)
An external monitor was not attached when sleeping it, so I don't think How to fix a Macbook that does not always draw its internal screen after waking from sleep and having unplugged external display while asleep? applies.
I've run gfxCardStatus, almost always in "force integrated mode" (to conserve battery). And normally it wakes up correctly.
I run VMware Fusion 4.
All software is up-to-date and fully patched.
I tried to plugin an HDMI monitor and switch displays with Command-Fn-F1 and Command-Fn-F2, but that did not help (it would not switch displays).Before trying to:
reboot (by force a power off),
reset SMC
and/or reset PRAM/NVRAM
What options do I have that do not loose my work?
sleep-wake retina-macbook-pro battery

Answer 1

Those keys do not reinstall OS X. To do that:
Reinstall Lion, Mountain Lion, or Mavericks without erasing drive
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Repair
When the recovery menu appears select Disk Utility. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list.  In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive.  If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported then click on the Repair Permissions button. When the process is completed, then quit DU and return to the main menu.
Reinstall Mountain Lion or Mavericks
OS X Mavericks- Reinstall OS X
OS X Mountain Lion- Reinstall OS X
OS X Lion- Reinstall Mac OS X
     Note: You will need an active Internet connection. I suggest using Ethernet
                 if possible because it is three times faster than wireless.
COMMAND-OPTION-P-R keys resets the PRAM. OS X keyboard shortcuts.