I had some similar issues with the cheapie SD card that came with my kit. No problems since I upgraded to an approved Sandisk card. You may want to power down and remove the battery if it acts up again.
earleinatruck ...and there was light...and it was good. The more I learn, the better my camera gets. D7000 w/MB-D11 Grip 50mm f1.8D 24mm f2.8 mf 10-24mm f3.5-4.5 G ED 18-200mm f3.5-5.6 GII ED 70-300mm f4.5-5.6 G 70-200mm f2.8 VRII TC 20E II SB 910 Tokina 35-200mm f4-5.6 Macro + 2X TC