Oh, forgot to mention I uploaded my "C:\Users\<Name>\AppData\Local\DayZ\" folder as Jim_DayZ.zip and my DxDiag as Jim_DxDiag.txt.
Hope the files are to any help.
Please tell if you want more information or uploads of other files and I'll provide them ASAP.
Just got the same error message. Have had the game almost since public release and this is the first time this error occur. Tried everything listed above with no luck. I'm not so fond with re-installing steam right now, so I'll wait with that to see if I can find another solution.
Will notify here if any progress is made from my side or if the error still occur.
Thanks