My guess would be a problem with your firewire driver. See below from Puremotion's web site for their overview of firewire options.

OHCI

We suggest that you only consider OHCI FireWire cards - see our article OHCI Explained for more details. An OHCI card will automatically be recognised by Windows 98, ME, 2000 and XP and will not need any additional drivers to be installed. Pretty much any DV-aware application will then be able to recognise the card and be able to use the DV devices (eg. camcorder) connected to it.

Non-OHCI cards may only work with the software that is bundled with the card, so we will not discuss these further.

Chips With That?

There are many FireWire chipsets out there, from manufacturers such as Texas Instruments (TI), Lucent, VIA, ALi and others. Whereas all the chipsets should work, we have found compatibility issues with non-TI chipsets. It is our experience, and that of many others if you read the Usenet newsgroups, that non-TI chipset FireWire cards can have compatibility problems with some motherboards.

It simply isn't documented well enough, but there are obviously many combinations of FireWire card and motherboard and we don't really want to label any particular brand as being "incompatible". We would say however that if we were to choose a chipset that was more compatible that most, it would be the TI chipset.

The TI chipset is probably the most popular, but tends to be in the slightly more expensive FireWire cards. Popular cards which use this chipset are the Pinnacle StudioDV and ADS Pyro cards, but there are many others. If you are tempted by a low cost FireWire card, we'd suggest that you find out which chipset it uses and search a resource like Google Groups (http://groups.google.com) to see if there are any known compatibility problems with the card.

Word Of Warning

Most FireWire cards come with some kind of bundled video editing software. You should be careful installing this software, as some packages will install the Texas Instruments camcorder driver, which is not necessary under Win98SE, ME, 2000 and XP. Note: this TI camcorder driver is not the same as the TI FireWire driver. The TI camcorder driver does not provide as much functionality as the default Microsoft driver and can cause compatibility and stability problems on your system.

Now, I realise that you may think that we're just trying to put you off installing software from our competitors. You are free to ignore this advice if you want, but we are trying to help here.

Summary

Choosing an OHCI FireWire card based on the Texas Instruments chipset will probably cause you the least amount of troubles. Cheaper, non-TI chipset cards may work just as well, but you should check to see if there are any known issues with your hardware. We would not recommend getting a non-OHCI card.