Well, I think that I finally have to upgrade my Final Cut Express HD – I can no longer capture DV on mt Mac Book Pro.
I have cleaned and defragged the hard disk – no help – I have plenty of free space.
Frame loss happens in Final Cut and in Quicktime.
This worked for a long time – then stopped.
So I will upgrade FC and see – the next step is to wipe te OS and start over.

Here are some notes:
Final Cut Pro: Dropped Frames and Loss of Audio Sync
http://docs.info.apple.com/article.html?artnum=58640
Final Cut Pro 3: How to delete the preferences file
http://docs.info.apple.com/article.html?artnum=31197