DVD and CDRW missing, but memory stick drive is still around.

[dcdomain]

Sony Vaio Computer
Harddrive and memory stick drive still shows up, but both the CDRW and DVD drives are missing. Under system properties, it states that the drivers are incorrect or not installed. What would cause it to suddenly lose the drivers in WinXP?

 

[dcdomain]

n/m, after a reboot and messing around with it, they are back...