[ubuntu] ubuntu guest os in vb 4.2.8-mounting shared folders problem

I have ubuntu as guest os in VBox. My ubuntu is
lvgandhi@lvgandhi-ubuntu-VirtualBox:~$ uname -a
Linux lvgandhi-ubuntu-VirtualBox 3.2.0-44-generic #69-Ubuntu SMP Thu May 16 17:35:01 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
I have mounted local folders as shared folders without auto mounting and have the following fstab additions
Lvg /media/Lvg vboxsf uid=1000,rw 0 0
Downloads /media/Downloads vboxsf uid=1000,rw 0 0
NOW2AMIJ /media/NOW2AMIJ vboxsf uid=1000,rw 0 0
It used to work until yesterday. Today shared folders are not getting mounted. Any solutions?