I am currently using Ubuntu 12.04.2 LTS installed from LiveCD. It works fine when system boots but after sometime it hangs for few seconds (about 2 to 4 seconds) showing a garbage screen and then becomes sluggish.
It happens every time I boot my system. I think that it is because of my graphics card driver. I have intel i845G 64 MB of graphics card. I have tried updating my xserver-xorg-video-intel graphics driver, but sometimes it becomes more sluggish at time of boot itself.
I am searching for this solution for a very long time but was not successful.