I started with Windows 7 on a Toshiba laptop, and wanted to add Ubuntu 11.04 in a dual boot configuration. I installed Ubuntu using the standard install, and it seems GRUB has detected both Windows and Ubuntu.

Ubuntu works fine, but when I try to boot Windows it will not load. It gets to the "starting Windows" animation, which plays for about two seconds, and then reboots the computer. It seems that none of the safe mode, etc., options do anything to help this problem.

Unfortunately, I have no idea how to even begin addressing this problem, since I can't even get into a command prompt in Windows. It seems that the partitions are fine (see below), but maybe there is something here I don't know.

If anyone has an idea on what I should try next, I'd greatly appreciate any suggestions. Thanks in advance for your assistance.

***@sctoshlinux:~$ sudo fdisk -l

[sudo] password for ***: 



Disk /dev/sda: 320.1 GB, 320072933376 bytes

255 heads, 63 sectors/track, 38913 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

Sector size (logical/physical): 512 bytes / 512 bytes    

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk identifier: 0xb7784a6c



   Device Boot      Start         End      Blocks   Id  System

/dev/sda1   *           1         192     1536000   27  Unknown

/dev/sda2             192       23548   187606782    7  HPFS/NTFS

/dev/sda3           37753       38914     9324544   17  Hidden HPFS/NTFS

/dev/sda4           23548       37753   114102273    5  Extended

/dev/sda5           23548       37264   110171136   83  Linux

/dev/sda6           37264       37753     3930112   82  Linux swap / Solaris



Partition table entries are not in disk order