When i try to download the adobe reader 10.1.3 update patch recommended by Secunia PSI, windows installer appears and say's "This patch package cannot be opened. Verify that the patch package exists and that you can access it, or contact the application vendor to verify that this is a valid Widows Installer Package".
It seems that the patch using which you are trying to update Reader 10.1.2 to 10.1.3 is corrupt.
Please be sure that you have Reader 10.1.2 installed and then update it using the following MSP file:
To install Reader 10.1.3. Here are the correct sequence, you need to follow
For more details, please refer to http://helpx.adobe.com/acrobat/kb/update-patch-acrobat-reader-10.html