I have met most of the problems that u guys posted,and I have install and uninstall the game for several times even reinstall my system.I am not expert at COM problems,by some small suggestions.
1.if you really like lotro and want to explore the world,reinstall your system for it or at least scan the whole computer(both highly suggested)
2.the exact size of the game is 12.3GB(the largest game I played).still i am curious about why my baby computer can dl it in only 2days.
3.when you have done dl the tutorial part,u can creat a character and get into the game,but it won't go much further before the fullgame dl is completed.
4.when full game dl was completed,pls reboot your computer,some settings can be self-perfected for lotro.(recommanded)
5.eeeeeeer...sorry I can't remeber any other none-technical tips by now,I will come up again if I remember something.
Finally,this game worth you to reinstall your system(and about Vista users,I'm sorry,i'm xp)