Check the server name or IP address, check your network connection, and then try again

I've got connected to the windows machine one day.

I used smb://MyServer, then I'd enter my login info

On the next day, when I try to connect again, I receive this message "Check the server name or IP address, check your network connection, and then try again"

I found some suggestions to include username and password right in that line such as smb://username:password@MServer/

And it worked, but again, on the next day, I was not able to login getting the same error message.

I also tried to use local ip address of that computer, didn't help.

The ping to that server was successful, I am also able to connect to that computer with other windows PCs.

I use MacBook Pro with OS X Lion 10.7.5. Didn't do any updates or any other changes since the first time I've got connection.

The only change happens, I take my laptop home for the night where it connects to my home router.

Can somebody please explain what's going on here or what else can I try?

Thanks