Have you ever connected your Flash Drive or some other USB removable storage and it just doesn't show up in XP?
One of the reasons for this peculiarity is that Windows XP will sometimes try to assign the removable storage device the same drive letter as another device that already exists on your system (i.e. CD Rom drive or even a mapped network drive).
Fortunately you can easily resolve this problem. From the Control Panel, open Administrative tools, then Computer Management. Then under Storage click on Disk Management.
From there you should be able to see the device, by right clicking and selecting ‘Change Drive Letter and Paths' you can change the drive letter assignment for the device - Just make sure that you look in My Computer or Explorer first to see what drive letters are already being used.
You may receive a warning notice that changing the letter might prevent some things that are seeing it currently will no longer be able to see it. Since it's not viewable anyway you can click yes to change the letter.
Have another look in My Computer - Hey Presto it's back.