Recently when I remotely log in to my computer I see a strange behaviour; I see some messages for "snap-in"; like "creating snap in" and ...;
could you please let me know what snap-in is? isn't a virus or some malicious software?
No problem - snap ins are tools (named after different types of engineering tools which snap into a common handset) to enable a number of different functions - in your case remote login and management functions. They do not repesent any sort of infection.