This is a know bug with the ATI2900 graphics card and possibly the ASUS PK5 Deluxe motherboard. dropping blur effects to low will get rid of it and you don't have to turn off post processing.
It has nothing to do with interfaces.
Check this thread
http://forums.lotro.com/showthread.p...t=strange+bars
and then BUG IT INGAME!
we all want this fixed and I don't think it is getting much attention.