MBP 17" unibody. Firewire 800 port not mounting or droppin

I have a MBP 17' quad core with 8gb of RAM, and a 500gb Hard drive. Whenever I hook up my external hard drive via the firewire 800 port it sometimes doesn't mount and when it finally does mount, it unmounts after a few minutes. I know the xternal drive is good because it mounts on all my other Macs, and it will aslo mount of my MC=BP using USB. I need to use the firewire drive because I am a Vido DJ and I need that port for my video DJ software. Why is this happening? Can someone help? Has this happened to anyone else? If so, how did you fix the problem. I've geard about permission and Firewire 800 with metal rings and also resetting the SMC? What are the steps I should take. This is frustrating!!!