I had installed Ark and Software Center. After that I tried 2 install some '.deb' package by clicking on it. It turned out that instead of an automatic installer just had two options to choose, namely Soft Center or Ark (used 'dolphin' browser). Tried to solve by uninstalling the both, but after it, happened that there is no any association. DOES ANYBODY KNOW HOW TO RESTORE THE DEFAULT ASSOCIATION OF '.deb' FILES? ( 'RAW' situation in that matter as just after have installed the system ) P.S. I am not interested to have fun with possessing and discovering some sys , would like to have a stable main system 4 others like windows (virtual machine to do heavy calculations, etc. ). Expect that the chosen SYS must be stable should not to surprise me with such complications or give by itself some simple solutions in such a matter. In fact am using kali 1.0 (debian wheezy), but had heard that it is almost similar to ubuntu that is build on debian in generall. Also use a kubuntu ditribution to test. Looking forward to having a smart advise, also 4 future potential similar problems.