Originally Posted by divijvaidya13
(As soon as the windows logo appears,it restarts!!!)
Do login with Ubuntu and back up your data on DVDs!!!
If you can see the win logo, it should enter the system by itself, this sounds like win 7 was altered.
Try to fix your bootloader first, in this case, GRUB.
if it doesnt work out...
I suggest you back up your data for safety, re-install vista and then install Ubuntu. Maybe you want to create a VFAT partition just for data, it's always safe and both operating system can write and read on it.