VPCS11V9E Firewire import not working - help needed

Good morning. I have a problem with my laptop (VPCS11V9E) - any DV video I import via firewire is very dark.

The laptop is 4yrs old, Sony, win7. I have tried 2 different cameras, different tapes, different firewire cables, different import software. Everything gives me the same result - very dark video. I borrowed a friend's laptop and imported the same video using the same equipment and it is perfect. So I am sure the issue is with my laptop.

The video (.avi format) is dark in the import window, dark in the editing software, and dark when played back on the laptop or a tv.

The video is not dark on the camera's lcd screen, and it is not dark if I connect the camera directly to the TV.

Given I have tried different software on my laptop, I guess software is not the problem. So I tried to change the firewire port driver. There are 3 firewire driver options on my laptop, but none of them fixed the problem.

I spent a few hours last weep updating the drivers from the sony website. THat didn't help, so then I re-installed the drivers using the built-in sony support program. Still no change.

I googled the problem but didn't find anything that could help. I don't have an express port on the laptop, so cannot try another firewire card. I really need the laptop to edit home videos.

Can anyone think of anything else I could try? Thank you for any help, Josh