grub2 - How to fix windows bootloader after grub install?

Ok, so that's what I did:
I installed ubuntu and when I had to chose the partitions and grub install I clicked on overwrite "windows bootloader" or something like that, now everytime I boot, grub shows ubuntu and windows, ubuntu works but if I choose windows grub send me back to itself. It's like the windows bootloader loads... grub. How can I fix that?

parted /dev/sda print
Model: ATA WDC WD3200BEVT-7 (scsi)
Disk /dev/sda: 320GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type      File system     Flags
 1      32.3kB  82.3MB  82.2MB  primary   fat16           diag
 2      82.8MB  10.8GB  10.7GB  primary   ext4
 3      10.8GB  317GB   307GB   primary   ntfs            boot
 4      317GB   320GB   2683MB  extended                  lba
 5      317GB   320GB   2683MB  logical   linux-swap(v1)

Windows part of my grub.cfg

### BEGIN /etc/grub.d/30_os-prober ###
menuentry "Windows 7 (loader) (on /dev/sda3)" --class windows --class os {
    insmod part_msdos
    insmod ntfs
    set root='(hd0,msdos3)'
    search --no-floppy --fs-uuid --set=root 7AF84223F841DE4F
    chainloader +1
}