HI,
Check two or three machine services.msc are you able to connect in your system.
Try this steps :
Run -> Services.msc ->Right Click on Services (Local) -> Connect to another computer -> Type computer name.
Check what happend did you able to connect system or received any error.
Check this artical also how to install remotaly by Psexec.tool
How to remotely Install Altiris Agent in an unmanaged firewalled machine
http://www.symantec.com/business/support/index?page=content&id=HOWTO8176