The drive is not ready for use

The drive is not ready for use; its door may be open. Please check drive \Device\Harddisk1\Partition1 and make sure that a disk is inserted and that the drive door is closed.
Cause

This article was previously published under Q222871 in Microsoft Help&Support
This behavior occurs because removable media can be reported as malfunctioning if a cartridge is not present in the removable media device.
When the disk controller BIOS queries a removable media device, it stores the device status information in memory. At startup, Windows NT sends a query to determine the status of devices connected to the disk controller. Depending on the firmware installed, the BIOS revision, or the characteristics of the disk controller, removable media can be reported as malfunctioning if a cartridge is not present in the removable media device.

If you don't have a floppy drive but the icon appears in the Hard Drives/Partitions XP window, then it's for improper BIOS settings
Solution
Disable the onboard FDD controller in BIOS, set the floppy drive a: 3.5" to 'not installed'
Or disable "nostalgic" floppy disk drive in Device Manager