Vista - laptop card reader won't read memory cards

I have a Dell studio laptop running Vista 32bit with a camera card
reader built in, but when I insert a memory card in the slot it doesn't
show up at all.

When I plug it in, you can hear the sound of a usb device being
recognized by windows, and the safely remove icon shows up on the
desktop system tray, but the card doesn't appear in windows explorer. It
shows up as a removable device in disk management but has no letter and
if you try to format it, disk management report that there is an error
and I should try restarting disk management or the computer (that
doesn't work either).

I suspect that there is a driver fault but I have reinstalled the memory
card reader drivers and nothing seems amiss in device manager

Can anyone please advise if this might be a hardware fault or if there
is some setting or software that needs to be installed for the card
reader to work correctly? What are the drivers that it needs?

I reformatted the computer a while back and I installed all the device
drivers but I may have missed some small patch setting to make the card
reader work, although there are no warnings in device manager about
non-functioning hardware.

Thanks for any advice.