I was getting this error earlier today when trying to start LoadRunner VUGen. I did a Google search and found the following post (which really wasn't any help.) http://www.sqaforums.com/showflat.php?Number=391309
I was able to "fix" it by running the setup.exe file again and selecting "Repair".
Sorry I didn't follow the posting instructions. I figured since I was answering my own question it would be ok.
I will say I'm using LR 9.1 and running Windows XP Pro SP3.
"It's a mere formality to go through QA."