i just came along this site: http://www.3dap.com/mafia/index1.htm and it seems the scrolling text on it somehow interacts with ls or some modules, it creates some really heavy flickering in some cases.
found this effect to happen only with rabidvwm and xlabel so far, but i'm too tired to do more research now ... good night :)
tried opera 7.5 and firefox 0.8.

maybe its got something to do with Java and those mods.

yup...its the version of the Sun Java Console you have installed. Upgrade it to a newer version and you should be ok.