Before installing your extra hard drive your dvd rom would of been drive D, after installing the extra hard drive, the hard drive would become D and the dvd rom would become E.
win dvd may still be looking for your DVD rom at position D rather than E.
Suggest reinstalling win dvd which should then see the drive as E rather than D. Also make sure DMA is activated for the DVD Rom.
Also make sure the jumpers for slave/master are set correctly on the new drive. And maybe swop drives around on the ide channels and make sure auto detect is set in the bios.