Recently, is appeared on Windows Update an Excel hotfix, the KB959995 update

But, on some computers, it is impossible to install... it simply fails, without any information

One of that computers, unfortunately, was my computer.... searching on Google, everybody was saying "you must reinstall office again".

But, i found a solution by myself:

First, download the patch from the Microsoft Website.

Run the patch and wait several minutes; after some time, you will get an error similar to "Impossible to find the installation files in E:"
Why? When I installed Office 2003 several years ago, I told him to save the installation files on E:
Over time, i added a new hdd, swapped partitions, and E: has become M:
E: has become an "unused space", so the patch is not able to find the installation files and it will fail

What to do? The easiest solution is making M: become E: again (I will write an howto on this, if requested)
If you managed to restore the original drive legger, you can go at the end of tutorial

If is not possible, you have to use the listool, downloading it from here.

After unzipping it, click on "move local installation source":

And then select a drive that can accept the setup files:

Now you are ready to install the patch. Run again the patch that you downloaded from the Microsoft website, wait several minutes, and you are done!