So...

I am running Xpress Pro, and trying to work with my DV camera and external LaCie drive attached at the same time. My MacBook Pro has both normal firewire (DV) and rectangular firewire 400 (for the external) ports. For some reason, both ports will not function at the same time. I have to import the footage onto my computer's hard drive, then disconnect the camera and connect the hard drive...you get the idea. Any help would be awesome!

Also - what is the best way to move/delete MXF Avid media files?

The rectangular firewire port is the for Firewire 800.  The one shaped like a arrowhead is for FW400.  Not clear how things are connected but sending the DV signal from the deck or camera thru a LaCie drive has been less than reliable.  You should be able to plug the drive into one port and the deck into the other as long as you don't have a Mojo.  (You might need a FW800 to FW400 cable to make the connections if the LaCie is FW400.)   If that doesn't seem to help, see if you can get a different firewire drive for a test to see if the problem goes away if you don't use the LaCie.

Best way to delete MXF media is using the Media Tool within the Avid.  Best way to move media is to become familiar with the Consolidate command.

 the two ports will probably not functions at the same time because they are using the same bus on the laptop.  get an add in firewire PC card, and that will probably fix your problem.

The two ports will function at the same time but share bandwidth if they're on the same bus.  It wouldn't make much sense for a manufacturer to install two ports and have only one function at a time as the resulting calls to tech support would be overwhelming.  DV and a Firewire disk combined will only consume maybe 25% of the available bandwidth so unless you've got a Mojo on the bus (it doesn't like to share at all) it shouldn't be a problem.

For general use, both ports function at the same time. However, with Pro Tools, MacBook Pro users were required to get a Firewire ExpressCard because it did not like multiple firewire devices on the same bus. I would not be surprised if Avid is the same.

First I would try a different drive if you have access to one, running one device into the 400 port and one into the 800. Daisy chaining a camera through your drive is unlikely to give good results.

If that doesn't work, I would move on to getting an ExpressCard adapter. Make sure the card is Mac compatible. Belkin and Siig are usually reliable manufacturers. Avoid cards that have both USB and Firewire. Just get a dedicated Firewire card.

Let us know how everything works out.

I have the same problem. I have been searching  for a solution for a long time..

I have a macbook pro.

Firewire 800

Firewire 400

LaCie 1Tb (Big disk extrem+) Which has Firewire 800, 400, USB

When I have the LaCie hooked up by way of FW 800 my DV camera won't work (hooked up to the FW 400 port)

It seems I will have to do the same as you and download all by DV footage to the Mac's hardrive, then transfer to the LaCie. BUT what a pain in the butt. I did not expect this from a Mac book "pro".

I use final cut 4.