Sp2 update never finishes

When exiting wordperfect X5,  a dialog pops up telling me I can install an update, but when I run the installation, the installation seems to run OK up to a percentage, then stops with no error message. In fact even trying to abort does not work at this point, I have to force the installation to stop, or shut the system down. I tried it too by downloading the file from the Corel website, with the same result (but at a different percentage).

What is the matter, and what can I do to get my system updated?