FCP problem solved: "Unable to locate timecode" error on batch capture

I spent a long time hunting around online for solutions to this problem and found plenty, but none of them had the virtue of actually working. Having found, almost by chance, the solution that worked, I thought I'd share it. 

Importing footage from two separate Canon Vixia HV30 camcorders using FCP 7, I began having increasing problems with batch captures and then even single-clip captures. It got to the point where the camera couldn't find any in-point or out-point under any circumstance. I tried cleaning the heads, trashing preferences, verifying and repairing permissions and disks - nothing made the slightest difference.

It turned out that the problem wasn't with the computer or the camera - it was with the external hard drive. What finally worked was changing my capture scratch disk. I was using a 2TB LaCie, and had about 150GB free on it, and when I switched to a second mostly empty 2TB LaCie, the problem cleared up instantly. So - if your capture scratch disk is getting toward 90 percent full, and you're having this time-shredding, madness-inducing problem, see if Santa will stuff your stocking with some free storage.