My BB doesn't recognize my SD card sometimes, no matter how many times I reboot it, but it works when I completely take out the battery and do a hard reboot of the BB. Hopefully that works if you haven't tried it!
After I transfered files between BB to PC,if I didnot check error of the card,the card will be not recognized by BB
so before we reject the BB from PC,check the error first.
right chick the BB in the fold "My computer",selcct "property", click "tools",click"check" in "check error",slect "auto repair the errors of file system"
then we can reject the BB.