Hi 
Dohhh, sorry. My turn for missing an earlier post! I hadn't realised you had already tried re-downloading. Sorry chap!
It is probably best for you to avoid the 3.6.0 at this point. Beta-testing pre-release versions is better after you have some idea of how to get back to safety. The 3.5.4 is probably the best version to install right now although a lot of us are sticking with the 3.4.6 on machines we can't fuss about with all the time. The 3rd point is roughly equivalent to a service pack so 3.4.6 is roughly like 3.4 Sp6. However the .4 is usually where a branch suddenly becomes very much more stable so i am moving towards getting that on all machines except the one i can really play around with where i will hopefully get time to test-drive the 3.6.0 before it gets released properly. It's always good to try the latest beta somewhere where you don't need to rely on it always working in order to get real work done.
We don't normally have all this trouble trying to install LibreOffice on Win7 which is why we are a bit stuck. Usually it just goes through really smoothly. On Xp i would usually approach pretty much any problem by defragging, disk-cleanup, running MS updates and rebooting but none of that should be causing problems for LibreOffice.
I think just pick a version of LO, it doesn't really mater which one. Then uninstall all other versions and try installing just the 1 again.
By the way do you have OpenOffice, NeoOffice, Lotus Symphony or any othe Office Suite installed on the machine? LO installs easily alongside MS Office but sometimes does have troubles alongside one of the OOo forks.
Regards from
Tom 