I have windows 7 and wanted top replace them with 12.04 but when I was booting and starting installation of ubuntu I chose replace windows in my ssd and it saw this problem. "/dev/sda contains GPT signatures, indicating that it has a GPT table. However,it does not have a valid fake msdos partition table, as it should. Perhaps it was corrupted-possibly by a program that doesn't understand GPT partition tables. Or perhaps you deleted the GPT table, and are now using an msdos partition table. Is this a GPT partition table?" Even when I click yes or no it does not move on it seem like a no responding situation. Do I need boot repair to solve it?
You just need to re-make the partition table, a quick fix. Boot off the LiveCD and select "try Ubuntu". Next run Gparted and select Device -> create partition table.
You can select advanced options which will give a menu where you can select GPT (GUID partition table) if want, and if the drive is larger than 2TB then I would recommend that you do so.
After you have have written a new partition table, you can select "install" and everything should go smoothly.