trouble setting up Iomega NAS drive

A while ago I picked up the 500GB Iomega NAS/USB drive. It's hooked up to a router connected to 2 computers: one wired, and one wireless. First of all I had a heck of a time connecting to the drive. But I turned off Zonealarm and it worked ok... saw the drive as "Public on Z" or something like that. Problem is that everytime I turn on the computer, I have to run the Iomega software and "mount" the drive, a process that sometimes does not work (tells me that subnets differ, connection failed). Do I need to be playing with IP addresses and settings in order to get this thing to connect reliably? I'm pretty ignorant about this stuff. Tried to read the manual and it really doesn't provide any information... says something about assigning an IP address but doesn't say HOW. If anyone can help me with this, it would be greatly appreciated. Thanks.