os-prober fails with chainloader on win7 partition

[Jürgen]

os-prober detects win7 partition and creates menuentry with chainloader+1 (see http://paste.ubuntu.com/10696096/),
 but loading win7 ends in black screen without returning to GRUB2 menu.
modified separate menuentry "11_Win7-Loader" (see below) in /etc/grub.d/ using ntldr instead works pretty well,
after disabling OS_Prober in /etc/default/grub: GRUB_DISABLE_OS_PROBER="true"

menuentry "Windows7 (loader) on sda2" --class windows --class os {
 savedefault
 insmod part_msdos
 insmod ntfs
 insmod ntldr
 set root='(hd0,msdos2)'
 search --no-floppy --fs-uuid --set=root DEF2805CF2803B33
 ntldr /bootmgr
}

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.