First, have you update your version 3 with the version 3.02 patch? This is very important -- especially if you are working on a system running other than Windows XP.
Second, I'm not quite clear where things are failing for you. Are you saying you're capturing miniDV over FireWire and that the program won't capture any further? If not, what type of camcorder is your video coming from and how are you getting it into your computer?
How fast is your processor, how much RAM do you have and how much free space is left on your C drive? Are you capturing your video to your C drive or to another drive?
You will likely need at least 20-30 gigs of free space on your C drive -- and it's very important that this drive be freshly defragmented. Fragmentation can cause the very symptoms you're describing, since the program need large chunks of free hard drive space for its paging and scratch files.
Welcome to the forum.
With Memory/Resource issues, this ARTICLE might prove useful.
For setting up a computer for an editing session, this ARTICLE might give you some tips. For editing video, one needs all the Memory and Resources available. Most computers are overloaded with bloatware, and cleaning that out, or stopping unnecessary programs, and processes, will help greatly.