Thanks Flavius,
I tried that but made no difference,I found this article in Microsoft Support and followed these steps, It seems to have fixed it. The icon has reappeared back in My Computer and the drive works like it used to.
:D
Windows Vista
Click Start, and then click All Programs.
Click Accessories, and then click Run.
Type regedit, and then click OK. If you are prompted for an administrator password or for a confirmation, type the password, or click Allow.
In the navigation pane, locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}
In the right pane, click UpperFilters.
Note You may also see an UpperFilters.bak registry entry. You do not have to remove that entry.[/B] Click UpperFilters only. If you do not see the UpperFilters registry entry, you still might have to remove the LowerFilters registry entry. To do this, go to step 8.
On the Edit menu, click Delete.
When you are prompted to confirm the deletion, click Yes.
In the right pane, click LowerFilters.
Note If you do not see the LowerFilters registry entry, unfortunately this content cannot help you any further. Go to the "Next Steps" section for information about how you can find more solutions or more help on the Microsoft Web site.
On the Edit menu, click Delete.
When you are prompted to confirm the deletion, click Yes.
Exit Registry Editor.
Restart the computer.
