I recently upgraded from Win 7 64 bit to Win 8 on my oldie but goodie Dell Latitude D620. I'm having issues related to closing the lid/sleep mode/restarting. I have already disabled the "fast startup" mode in control panel, and this has not solved my issues. Every time I close the lid, which should put it into sleep mode, and I open it up at a later time, it will boot up but always give me an annoying message about you computer has recovered from an error message, and anything I had left open (a word doc, powerpoint, or browser) disappears. Also, when I shutdown the computer via windows, it only restarts it and I get a the blue windows error screen with a smiley face and some sort of error about system thread exception error. I'm not sure what else to do, and these are rather annoying issues as I encounter them daily
The Dell Latitude D620 is from way back in the WinXP days. Dell doesn't really even support Windows 7 on that one. Best bet would be to replace the laptop with one specifically built with Windows 8 in mind. Otherwise very good luck in finding updated drivers.
Your issue is most likely a driver issue. Dell doesn't appear to have provided any Windows 7 drivers let alone Windows 8 drivers. I hate to say it as I really do like Windows 8 but you may need put Windows 7 back on that thing.