boot - Grub2 does not load windows loader in multiboot system

I clean installed windows 7 in legacy BIOS mode on a primary partition. I created two logical partitions for file storage. Ubuntu 16.10 was installed later using bootable USB by selecting the option 'Install alongside windows'. I think the setup created an ext4 partition to install Ubuntu.

Now when I switch on, Grub2 offers options to boot 'Ubuntu' and 'Windows 7 loader'. When I select 'Windows 7 loader' sometimes the black loader appears properly with options to boot Windows 7 or Ubuntu. But sometimes the screen just displays slanting dashed lines through.
Slanted dashed lines.
However instead of pressing 'Enter' on 'Windows 7 loader' option if I press 'E' I am presented with a code that can be modified.

setparams 'Windows 7 (loader) (on /dev/sda1)'
   insmod part1_msdos
   insmod ntfs
   set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
 search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd-,msdos1 --hint-baremetal=ahci0,msdos1 2210A74B10A7252F

else
 search --no-floppy --fs-uuid --set=root 2210A74B10A7252F
fi
parttool ${root} hidden-
chainloader +1

If I press F10 without modifying anything the 'Windows 7 loader' appears. This problem occurs randomly without a pattern.

After somehow reaching the 'Windows 7 loader', selecting the Ubuntu option does not take me to Grub menu. I am presented with a screen with grub at the command prompt.

Grub command prompt.

Solutions attempted:
Windows7 : Installed 'EasyBCD2.3' and selected 'Recreate all boot files' option
Ubuntu : sudo update-grub sudo update-grub2 and 'Ubuntu boot-repair'

Problem still persists. Advance apologies for the low res photos.