Acrobat 8 has not been tested and is incompatible on Windows 8.
Please upgrade to Acrobat 11.
You need not install Acrobat 8 if you upgrade to Acrobat 11.
The serial number of the older version will suffice as during the installation of Acrobat 11 it will prompt you to enter the previous qualifying version serial number and the current serial number (Acrobat 11) you own.
Enter the Acrobat 8 / 11 serial number when prompted and it will be fine.