Can't rename state file: Error -1
From Unofficial BOINC Wiki
Can be fixed by:
Please exit BOINC (File->Exit in Boinc Manager). Start->Run, type cmd and hit Enter. In the Window that opens, type chkdsk and hit Enter.
If BOINC is on a different drive than the command window that just opens is, type chkdsk driveletter: ... example given, chkdsk d:
Let checkdisk run, repair any mistakes. If it asks that Windows should be rebooted to do the external chkdsk, do so. Then when it's done and/or you're back in Windows, restart BOINC