Is there a limit to the number of drive letters allocated to drives? I have just bought a USB SDHC Card Reader. I previously had drive letters allocated from C to M When I plugged it in I found I had lost a partition on my external HD as the device had used one of the partition letters - the external HD had not been switched on. In Computer Management I found that the external partition had been changed to N but it didn't show up as such in Computer. I got the partition access back by changing the drive letter to it's former designation . The USB reader then showed up as N in Computer management but was not visible in Computer. I have now changed the new device letter to A as I have no floppy drive. I can now access all drives and card readers from Computer. I should explain that I have two internal drives with partitions C,D and E, a built in Card Reader using G,H,I and J, external drive K and L, two DVD drives F and M and now the new Card Reader A. All now show in Computer but Reader A does not Auto Run. As I will be using the Reader for photo access so I really need it to Auto Run. Any suggestions or explanations would be welcome.