Second hard drive not showing in My Computer

I have two hard drives. The slave drive I configured in Disk Management to use I: but it does not show up in My Computer. If I go to Start and Run "I:\" then the folder opens and is fully accessible, so it is not a missing driver problem. I have used this hard drive before as my master and just bought the other drive today. If I change the slave drive to use some other letter -- specifically some drive letter that comes before my CD-ROM letters -- then it shows up properly in My Computer. What do you think is wrong?