This question already has an answer here:
I tried to do an update to my system (12.04 LTA 64bit, on ACER aspire V5) got this:
Could not initialize the package information
An unresolvable problem occurred while initializing the package information.
Please report this bug against the 'update-manager' package and include the following error message:
E:Encountered a section with no Package: header, E:Problem with MergeList /var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_precise-security_main_binary-i386_Packages, E:The package lists or status file could not be parsed or opened.