Since My Computer is just a version of Windows Explorer I can't imagine why it is not showing up there.
What happens if;
1] Open My Computer, click the "Folders" button in the button toolbar at the top? This changes My Computer to Windows Explorer. Do the missing drives appear in the left hand pane?
2] Open a Windows Explorer window. Highlight My Computer. Do the missing drives display in the right hand pane?
Do the missing drives appear in the Device Manager?
If you downloaded and installed Microsoft's Powertoys TweakUI for XP, what shows up in it's My Computer > Drives section. Can you select those drives, or if they are already selected, de-select them, Apply/OK out, then open TweakUI again and re-select them?
Just a note. If you can highlight Desktop in any Save As window, you should still be able to 'backtrack' to any of the other drives.
I have a VERY strange issue. I recently "upgraded" back to Windows XP after a less then stellar experience with Vista. I backed up my files and did a fresh install of a slipstreamed copy of XP, SP3. Once installed and updated, I began reinstalling my applications. During this process I noticed that none of the local drives were visible in My Computer BUT they are visible in Disk Management and Windows Explorer. These are the attached devices:
A: = Floppy Drive
C: = 1 TB Internal SATA drive
D: = External USB 1 TB eSATA Drive
E: = Interal 100 MB Zip drive
F: = DVDR Drive
This has me stumped. I have checked all of the settings I could find relating to hiding drives/folder for security reasons and those are all set to default (i.e. the drives SHOULD be visible). I just find it very odd that they show up in Explorer but not in My Computer. The reason this is an issue for me is that when I download something or try to open/save a file from within an application like Word or Photoshop, I cannot browse to that file's location; my only choices are Recent Documents, Desktop, My Documents, and My Network Places.
Any help is greatly appreciated.