I use a Panasonic miniDV digital camcorder to tape my sons football games. I use Pinnacle Studio to download from the tape and make DVD's. I'm currently in my 4th season of doing this, but for some reason, this year, I can't get more than 5 minutes into it before my computer crashes. I get either a blue screen telling me the system has halted, or the screen locks up, or most commonly, the computer just resets and starts the boot up sequence. I've tried different software applications, 3 different hard drives, I bought a new firewire card, but nothing has helped. I also uninstalled and updated any driver I could find an update for.
I've had no other problems with this computer acting this way. I have a P4 with 2 GB of memory. I only time I experience problems is when I plug that camera into the firewire. I also used a computer at work to download from the camera with no problem. Today I'm going to try a new firewire cable, but I hold little hope for that.
The thing is, it all used to work and I can't figure out what's changed. Has anyone got any ideas, before I pull all my hair out?

I don't think it's the cable either. When the computer spontaneously reboots it's often due to a Registry mess up. You could try cleaning the Registry with something like CCleaner or doing a System Restore to a date when it was working properly.

NK is right. I would also suspect my video card before anything else.

The old "it used to work and now it doesn't" falls into two categories:
- a piece of hardware is failing
- software adjustments over the years have created an unstable situation (hard to figure out)

If this is your primary computer, perhaps a backup of all your data and a factory restore/reinstall could help, too.