My laucher stucks at 33%/99% and the comes with this when i try to download the file "mod_man.dat"
This is how the error looks like:
Update Failed
Failed to download or extract all required update files after several attempts. Please ensure that you have stable Internet connection, and that you have sufficient hard disk space.
(Error: 0xc1e90006)

And i got stable net and got 1 terebite/ TB / 1000GB left on my hard disk, so i cant really find the problem, plz help

Try running it as administrator (or disabling UAC)
or antivirus

Something in your system appears to be blocking LoL from disk access for some reason
maybe your antivirus thought mod_man.dat is a virus

kk, i will try to turn all my antivirus and FW off

but wtf is UAC?

User Account Control (google: disable UAC)
the thing in Vista and Win7 that pops up everytime making whole screen fade and asking you if you want to do it when you click on something with shield icon on it

It didn't work. Any other advise? maby some help from riot themself?

where can i find that option?

Answer from Riot can be obtained by submitting a support ticket
http://support.leagueoflegends.com/
They usually respond in 1-3 days

maby your net work are to slow or maby it stops working