Virus.. Cant open my word, excel.....

I have one computer that have been infected by a virus and when ever i open any forlder, i get i file in it that is called Decrypt-Instruction , 2 web file and one note file asking money to open the files, how can i detect if this virus is spread on othere system and will my symantic endpoint 12.1 detect it, i cant afford losing more files.

any update should i install or its auto.

I have attaeched the files that came and one execle sheet witht the error, if any one can help..

Thanks

Wael Hilal