From that error it sounds like the ‘skin.srf’ file somehow got corrupted. On my laptop here it is located in this folder:
“C:\Program Files (x86)\Steinberg\Cubase 7\Skins\skin.srf”
Obviously you are running another Cubase version, so you should look for it in the corresponding Cubase program files folder. You could try to do a ‘repair’ on the Cubase installation from the Windows ‘programs and features’ tool:
start → run → appwiz.cpl → press [enter]
or:
Press the Windows logo key + R simultaneously → appwiz.cpl → press [enter]
You’ll need the Cubase DVD (or atleast the Cubase installation files) for this.
Ideally, this will scan all Cubase installation files and repair/replace any corrupted files, including the (probably) corrupted skin.srf file. Or if you have another computer with Cubase you can perhaps copy it from there. The file might even be found on the Cubase installation DVD (though not likely as it’ll probably be compressed into some cabinet file or something).
Good luck!