Solved: Windows Explorer Not Recognizing Drive

XP-SP3

I have a 1 TB USB drive that Windows Explorer sometimes recognizes, and sometimes doesn't recognize. In this case it is the P: drive

Windows Explorer/My Computer has no listing for P: Refreshing the display and closing/reopening Windows Explorer/My Computer have no effect on the display of the drives and files.
However,

• Disk Manager sees the P: drive as P: drive and gives all of the expected information: size, free space, format type, etc.
• A command window sees the P: drive and can perform normal disk operations such as dir, copy and del files on the P: drive AND copy and del files to and from other drives AND create and remove directories on the P: drive
• Acronis True Image is, as we speak, creating an image of E: drive and saving the image to the P: drive.I assume it is saving the image file to P:\e-drive.tib since
  1. the process has been running for 20 or so minutes, and in a command window there is a directory entry for P:\e-drive.tib - 0 length, dated 20 or so minutes ago (the zero length display is SOP for Acronis during an image creation)
  2. the drive activity lights on the PC and on the P: drive are blinking steadily

It's clear that Windows acknowledges the P: drive, and only Windows Explorer has a problem displaying the P: drive, and then only sometimes ... sometimes Explorer acts as it should - meaning that it displays P: drive and can perform file operations on it.

What's wrong, and how do I fix it?