Morning i have Dell D 520 laptop bought off ebay two years ago and it as been a good one ,just recently i upgraded the memory from 512 to 1 mb.when i put it back together, some of the keys didn't work.so i installed a new keyboard.but i got the same result. the laptop works fine with a external key board.i have left the 1mb memory stick in. so its' not that,could it be the motherboard,or somthing less severe.can anyone help.
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Did you remove the keyboard to install the ram? Sounds like you didn't connect the cable correctly