P2 Card problems

Shot a concert yesterday with
HVX-200
4 / 8GB cards
and
1 / 4GB card
shot in
720 30p because that is exactly what the producer wanted me to do it in.
7 other cameras shot in DVX 100s at 24p which
producer said thats really 29.97 and my settings had to be 720 30p so they could match up in speed.
Can someone explain that to me a little more clear please thank you.

I was downloading to a 17 inch powerbook G4 with FCPstudio 1
threw its slot on the side of the laptop onto an external HD

At about the 5th load 1 of the loads has a corrupted file and the thumbnail was blank.
instead of reading ZYA00143 or something like that it was just pure 00000000
so that card would carry like 3 takes or 3 clips and only 2 would come threw.

i kept going but then at about the 9th load it happened again and then again about the 11th load and i had to put a stop to it so i reverted to SD tape because it was freaking me out.

Does anyone have any ideas what may have happened?

Thanks.


Bonus question
When i received card "B" from being loaded into the computer
i would get it back while im on stage.
then during a break

I would take card "B" put it into the camera EJECT card "A" so i don't format the wrong one.
Format card "B" now its clear, and then put Card "A" back into the camera
but for some reason card "A" was then blank
it happened to me a few times on set

Any ideas on that.
I paid close attention and i know i didnt format the wrong card but it behaved as if it was blank.

Thank you in advanced