Thanks for the drive information. I still have a couple more questions for you. I've been looking on Toshiba's support site but I cannot narrow the search because the model that you gave did not appear in the choices. For example, here is one page that I got when I narrowed my search to Satellite and a model that included the term 505D: http://goo.gl/nE7UC
I then narrowed it to drivers for Vista x64 but nothing came up. I'm thinking that you have more characters to your model number other than 505D. Can you kindly check to see what they may be? It should be on the laptop itself (often a sticker on the bottom) or in the documetation that came with the laptop when you purchased it.
Is the Matshita DVD-RAM the original optical drive or did you replace the original drive with it at a later time? I ask because an SATA device can be tricky to set up if the laptop wasn't originally set up for it (it has to do with something called the BIOS).
Was your laptop originally Windows Vista or was it XP that was upgraded later? Which version of Vista is it--Home Premium or another version? Often there is a difference with how drivers behave when moving from one Operating System to another.
Did you install any other software or hardware (such as a printer) right before you had the trouble? Sometimes there can be driver conflicts.
When you go to Windows Update in the Control Panel do you see any optional updates listed that apply to your device?
Have you checked the Device manager to see if there are any yellow triangles (an indication of trouble) and/or error messages?
I have seen many posts online with problems similar to yours with the same optical drive for different laptop manufacturers so it may be more specific to the drive than your laptop. It also can simply be a dirty or failing drive (how old is it?) Again, having a few more details from you might help us to help you.
This last comment is for Gary: I saw suggestions for deleting the upper and lower filters. I did that for a donated computer at school that kept "losing" both optical drives but it was only a temporary solution (and we eventually ditched the computer as too time-consuming for troubleshooting an old device). Do you think that's worth a try in this case? I hesitate to suggest it since it involves the registry and many people are not comfortable doing that even if they export a copy as a backup first.