try this...
1.When the installer pops up the error, ignore it. Dont close or cancel the install, just let it sit.
2.Perform a Windows search for proof.msi. You may need to select the Search system folders option.
3.In the results, you will see proof.msi located somewhere in the Windows temporary directory.
4.Copy, or write down, the path that is found.
5.Return to the installer. You should still have the error message present asking you to enter a location. In the box at the bottom of the error message, type or paste the path from step 4.
6.Now that you have the path typed/pasted, delete the proofing.en-us\proof.en\proof.msi part from it.
7.Press enter