Hello, first of all I apoligize for my english (i am italian). I got a similar trouble (or perhaps the same). I got the pro version of "Malwarebyte's Antimalware" (version 1.51.0.1200)and since several weeks the program is not able anymore to download and install the new definitions. The following error message appears: How can I solve this problem, please? The program has worked properly for a few weeks after I installed it in my PC (OS: Vista Home Premium 32bit SP2) , then update function has suddenly (and without any apparent reason) stopped working. many thanks