Nina, the most important thing to do when installing any new progran is to make sure you have ALL other running programs, except EXPLORER (your Windows program) and SYSTRAY closed down. You do this by pressing CTRL-ALT-DELETE, highlighting any programs listed, one at a time (except the above two),then clicking on END TASK. Once that is done, then proceed to do normal Windows install: START|SETTINGS|CONTROL PANEL|ADD/REMOVE PROGRAMS and browsing to where you have the download saved. If you have a partial install left over from your previous attempt, make sure that is deleted first. The reason for following these steps, is to avoid any conflicts between "shared files" such as DLL files. If one of the files needed during an install is being used by another program running on your computer, it may cause faults such as you encountered.
If you still have problems with your "Install Shield" (which is actually "ikernel"), you may need to re-install the ikernel.exe file again. You can do this by going to this site: http://support.installshield.com/http://support.installshield.com/ In the SEARCH THE KNOWLEDGE BASE box type: ikernel.exe Click GO On the next page in ADVANCED SEARCH, type: Q105097 Click SEARCH On the next page click on: Q105097 INFO: Install the latest version of ikernel.exe You will then be at the DOWNLOAD site. And follow the download procedure from there.
But the first procedure should see you well on the way to having PAF 5 up and running, so this (the last suggestion) is just an "emergency" procedure, in case you need it :-)