how to see other people's facebook account on your computer network?

[Night_Wolf]

ok , a guy from work said he saw my face book account activities and he is not on my friend list
he said he downloaded a pc application that allows him to see other people who are using the network computers to see their accounts , emails , passwords , etc
I am very private person , is this true , and if it is
is there any programs to block such attempts or warn me from that ?
i want to block my pc from such programs
thanks
@$ayit - it is not like that , it is like he can see what is on my pc ( kinda like team viewer or skype desktop share ) , which there is no such programs on my pc.
@ Camille - he said he is using hacker programs , i have kasper Internet security on my pc installed , so it should gives me a warning or something if someone is trying to preview my pc
@ midnight - god i hope so , but he seemed pretty sure what he is talking about

[Midnight]

he is just bluffing.
such a thing isn't possible.

[$ayit]

ASK him whats on it? What you have set up on ur pages...friends etc...If you don't have your FB account set up on Private & all, anyone can see it simple by goggling your name. I use a fictitious name... a title so its harder for ppl to find me. I block my AUDIENCE on the AUDIENCE selector on the post & things I send. (STATUS i.e) I rarely use 'PUBLIC" cuz anyone can see your FB things u have set on public. You can go to your account & Select these optio where u set up your FB account from the beginning too...ask what he seen & if he can't answer then ur problems are 1/2 way over. NO ONES private on air...it's never f100% Full Proof... the best thing is if you are invisible & not out there...if?

[Camille]

it does not seem like it would be possible but he must be a hacker.