Hello, My computer is Windows XP Professional. Recently I have been receiving several error messages that I don't know what they mean: "The instruction at 0x009c415b referenced memory at 0x00000000, the memory could not be written." " The instruction at 0x0278415b etc,etc. " The instruction at 0x02f6415b etc, etc. Besides, the computer has become very slow and I am unable to access many files, mainly avi. Could these messages be related to security issues ? Because they started appearing after I installed Nod32 antivirus trial version. If this is the case, could anyone please recommend a reliable firewall and antivirus program for me to install. If not, what is the problem? Appreciate your help.