Windows 7 may be there in the form of the hidden Image. If so, you can probably press the appropriate F-Key on startup to initialize the restore process which will overwrite W8.
If it doesn't start you may have overwritten it. If it does it will overwrite everything so any data/settings will be gone.
Not sure why W8 is crashing as it's usually quite stable. You might try looking at Device Manager and see if any error pop up. If you didn't do a "CLEAN" install of W8 that may be your problem.
So if you did an "UPGRADE" which kept your settings and applications that may be the source of your problems. If you reinstall cleanly and things seem stable you should update the VIDEO drivers from AMD, NVIDIA or INTEL as appropriate by having the site SCAN your laptop and recommend the drivers. Note you usually need the drivers from the laptop site as the manufacturer adds links into their version of Windows but installing W8 makes it possible to use the generic and likely much newer drivers from the main sites.
Other:
a) recommend Start8, or
b) wait and install W10
W10 is a free upgrade for W7/W8 users once released which may come as early as July 2015.