The root cause of the problem reported in Got ORA-01031 when logging on remotely using SYS AS SYSDBA appears to be a dodgy disk drive.
As noted in my updated Wiki entry (Got ORA-01031 when logging on remotely using SYS AS SYDBA, the solution is to install the Oracle Home on a disk drive that does not have as many I/O errors.
To that end, I brought a new Toshiba laptop with Windows 8 (64-bit), 16GB RAM, and 1.5TB of disk space. Unfortunately, Oracle RDBMS 11.2 is not supported on Windows 8. When I tried to install it anyway, the OS prerequisite check failed.
So my personal edition of Oracle RDBMS is in a hiatus at this stage.