Installation Failed after Windows Patching

Hi All,

In Windows server- 2008, after windows patching we tried to upgrade the SEP client from 12 to 14. At the time of installtion it promted an error "Windows installer not letting you to install". So we tried executing the windows installer from the SEP installtion package, that too dint help. Then we tried installing the same SEP 12, even that installtion also failed. So we asked the windows patching team to revoke the patches.Even after removing the patches, installtion failed.

In every installtion we are getting the same error "Windows installer not letting you to install the SEP"

May i know what will be the root cause for this issue. 

Regards & Thanks,

Harish