win 7 won't recognise sd card-why?

[airrunner]

I have a camcorder which has a standard sd card 2 gb. When i pop it in the usb drive it instantly shows all my photos and video files but when i want to copy them to the computer it says it cannot find these files and shows that the card is empty.
When i take it back out and pop it back in it displays everything again. Only when i try to play a file or copy them to the comp it will not do it.

Any ideas what the problem is? it's not the card reader nor the card they both work perfect in my other pc with win xp it's just win 7.

Many thanks in advanced to all

 

[airrunner]

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[veryrandom101]

are you plugging it into a front usb port? if so, try in one of the back. this might be a lame answer too, but have you checked your bios and made sure that usb mode is set to support both 1.0 and 2.0?