Hello from France
Welcome to the Autodesk/AutoCAD Forums
1) Windows 8.1 needs 2015 versions ... So you are lucky if your MAP 2014 is running on Win 8.1
AutoCAD 2014 versions + SP 2.x supports Windows 8.0 NOT Win 8.1 ...
2) Have you tried to open your DWGs in RECOVER Mode ?
( If the problem is on some specific DWGs !? )
3) Have you installed the SP 1 on your MAP 2014 ?
But PLEASE BE CAREFUL (Installing it or not is YOUR choice and you can't roll back !),
some people have their 2014 versions running OK on Win 8.1 WITHOUT SP 1
and RUNNING NOT AT ALL as soon as the SP 1 has been installed ...
Patrice ( Supporting Troops ) - Autodesk Expert Elite
If you are happy with my answer please mark "Accept as Solution" and if very happy please give me a Kudos (Felicitations) - Thanks
Patrice BRAUD