I had Win7 32 bit, then i installed ubuntu 12.10 along with win7. Both worked fine untill i decided to remove 32bit Win7 and install 64bit Win7. To do it, I inserted a Bootable Win7 DVD and restarted the laptop. when laptop rebooted from CD and copied files, i selected to delete the partition which Win7 32 bit OS. after a while system got struck, then i restarted. This time after booting from Win7 DVD & copying files, win7 installation didn't go further beyond showing the Win7 logo.
I rebooted the laptop, and win7 installation got struck at showing the Win7 logo. I thought DVD might be having some trouble, so i removed DVD & restarted I got error:
No such partition found
Then i tried to boot from Ubuntu Live CD, it showing error o Kernel Panic - Not Synching etc etc.