Problem Upgrading to 2009

Hi,Not sure if anyone else has experienced this but I am unable to either upgrade from 2008 to 2009, or to install 2009 from scratch on our work computers. When trying either method, the files look to install OK and I register the product but when trying to launch it the Windows Installer kicks in saying 'Preparing to install' and promptly dies. I have to use the Task Manager to stop the process as it is 'no longer responding'. Our Lectora reseller has tried to help and also forwarded the query to Trivantis, but after trying unistalling/reinstalling a couple of times it now looks like they've given up as they've apparently not come across this problem before.I've therefore had to reinstall 2008 from scratch + SP2 and am now left wondering if there's any point us continuing with Lectora if we're unable to upgrade (especially when we've paid for this as part of our maintenance).Any help gratefully received, as I'm really hacked off with it now.Thanks