I have exactly the same problem here recently with my Slimtype SDW-431S DVD writer. It's built in an Acer Aspire 1620 series notebook.
When I insert any kind of cd/dvd I can hear the drive taking effort to read, it ticks sometimes, and then it stops turning the disc as if no cd/dvd is in it. Even when I put a blanc cd rom in it and try to write it, Nero asks me to insert a disc, while one is in.
I tried to clean the lens with a cleaner, because of all the discs I tried only 3 of 'em in the end can be read with a lot of effort (these are a pressed CDrom, a pressed DVD and the last DVD burned with this drive, shortly afterwards the described problems showed up). When eventually the DVD's are playing, it stutters a lot and is hardly 'viewable'.
I also read somewhere someting bugging with Nero, so I updated it, in vein. Then I uninstalled Nero (6) :doh:
This is completely new for me (hardware failures) so I don't know what to do. I read a lot about firmware upgrading/updating, but as it is all new terrain to me I'm hesitating to mess up with this stuff.
So any help, suggestions and accompany will be very useful to me
Thanks in advance