It seems that the installation package did not download correctly. Before running it, please check that it is unaltered and complete by verifying it’s digital signature.
In Windows Explorer, right-click the .msi-file, select properties and the ‘Digital Signatures’ tab. Verify that it is OK. If not, download again and verify.
Also, do verify that you are using the right ‘bitness’ – 32-bit for 32-bit Windows and 64-bit for 64-bit.
Finally, if you’re upgrading, ensure that you have not run any ‘cleaners’ that delete old installation files and such. They are needed for uninstalls and upgrades.