|How many drives do you have? If there is an exclamation mark next to the drive in device manager, right click on the drive and go to properties. If it has a message on that screen like "Device Drivers Not Installed", then you have a problem with a driver. |
If you have 2 drives and they are IDE, check the jumpers on the drive, If you put them to cable select when they were installed, try changing one to Master and one to Slave. If they are both on master, change one to slave, if they are both on slave, change one to master. If there is one master and one slave, change both drives to Cable Select.
It this doesn't help, try connecting only one drive and see what happens.