Mike,
This problem happens in most cases due to system corruption or people
disabling their cryptography services.
Please try the following steps to see if it resolves the issue.
1) Make sure your cryptography services are enabled. To do this, go to my
computer | manage | services and applications | services. Then go to
cryptography services properties and make sure the service is started and
startup type is set to automatic.
2) If you are running Windows on a FAT32 drive, run scandisk.
3) If you are upgrading over DX8.1 debug, remove %windir%\System32\dxxpdbg
directory.
4) Try the resolution steps in
http://support.microsoft.com/default.aspx?scid=kb;EN-US;326815
5) Try the resolution steps in
http://support.microsoft.com/default.aspx?scid=kb;en-us;813442
6) Remove temporary files in %temp% and (if installing end-user runtime)
%windir%\system32\directx\websetup
Hope this works for you,
Robert Harper
WHQL Network Issues
WHQLNET at Microsoft.com