unable to install ubuntu 12 lts alongside windows7

respected all,

this is my first post to this forum. my problem is that i want to install ubuntu 12 lts version alongside window 7 but when i tried to install it it jiust show me loading but nothing hAppens even after a long time. i have tried both from bootable usb stick and also from the bootable dvd. but failed.

plz suggest some help.