program system error package list

dear all,

i get an error message appearing in the middle of my screen several times each session titled "program system error". also a "no go" icon in the systen tray, i get an error message and a suggestion that i have packages with unmet dependancies and should open package manager.

Opening package manager i get the following error message before it closes:

E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_trusty-security_main_i18n_Translation-en
E: The package lists or status file could not be parsed or opened.
E: _cache->open() failed, please report.

if i run 'sudo apt-get check' i get this:

viktor@viktor-SATELLITE-L750:~$ sudo apt-get check
Reading package lists... Error!
E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_trusty-security_main_i18n_Translation-en
E: The package lists or status file could not be parsed or opened.

Everything seems to be working normally apart from that. Don't know if i can install programs and can not check because my connection with internet is very limited for the moment.

Is this a serious problem? Is there any way to fix this?

thanks in advance for any suggestions