Why does my video stop all of a sudden on my d7000?

Sometimes when I'm recording Full HD video with my Nikon D7000 it only records for about 30 seconds and then just says 'video recording has stopped unexpectedly'. Something like that anyway.
Does anyone know why? I'm using a Panasonic SDHC 8GB class 10 card with read 90, write 25mb/s.
It doesn't do it all the time. For instance I just recorded a 2 min. Clip. No issues.
Does anyone know why it would be doing this? Or has it happened to you?
Thanks

Oh and Jim A, before you say "Read your manual" I have read it.

Added (1). I do have a SanDisk Extreme class 10 45mb/s card as well and its a 16GB. Picked that baby up for about $35 on sale at best buy. I have that in my #1 slot for pictures and the panny card in #2 slot for video. Maybe I should switch them.

Okay Ry, I won't say "read your manual". You know that's a major short coming of so many who buy new cameras, the manual ends up in the trash. Good for you.

Okay. You're using a class 10 card, that's good for video however did you format the card in the camera before using it? That's also a major short coming, people don't read the instructions for these cards and format them in the camera. Without being formatted they will act erratic like this.

The only other possible solution I can see if you know the format has been done or if you do a
re-format (which should be done after every upload) after making sure your files are safe on your system and it still behaves the same way, I'd replace the card.

These things aren't always perfect and that's about the only solution other than what I've written above. If this card is new then I'd return it for a possible exchange or refund. If it's an older card just replace it. You're using the size (8gb) that I find works the best.

Best of luck

It sounds like the SD card is not keeping up. The data rate changes a lot depending on what you are shooting.

Even though that Panny card is rated at Class 10 / 25mbps speed, they can vary widely.

It would very much be worth testing your camera with a card that has proven to be able to capture very high data rate video: the SanDisk Extreme Pro series is used by pros that hack cameras to get unbelievable data rates for the best quality video capture. They are not cheap, running about $64 USD for a 32 GB card, but they seem to be the most reliable.

If your camera stops unexpectedly with those card, the problem is definitely elsewhere.

Your sensor is overheating.

AVDADDY may have something

Do you know that once you activate live view, the cameras sensor starts to heat up. I have seen many people who are attempting to use a dSLR as a video camera, use the live view mode to set up the shot rather than looking through the viewfinder to compose and check the lighting in their video takes.

The whole time live view is activated, the sensor begins to heat up. At some point, the camera will shut down to protect the sensor. This is only true of cameras that have CMOS sensors (all dSLR's with a video feature use theses sensors). Actual video cameras use 3-CCD's so do not experience high temperatures at those sensors.