You are quite correct I've encountered this exact issue before on these forums where the person had installed the game on a secondary drive and reinstalling it to the Program Files directory solved the issue.
Originally Posted by Peresbert
Lightattack, you need to clear some space on your C: partition (drive) and reinstall the game client to the intended location.
[center][url=http://forums.lotro.com/showthread.php?18699-How-to-get-help-on-the-Tech-Forums-and-how-to-contact-Turbine][color=gold]How to get help on the Tech Forums and how to contact Turbine[/color][/url]
[color=green]Please reply to the topic or PM me if a solution I posted works for you: The more data I can gather the better I can help.[/color][/center]