Dvd rom missing

Hello,
my cpu is windows xp home edition 32 bit, i have two dvd rom's in my cpu they are working, recently i bought windows 7 i installed, LG dvd rom is working, but ultima dvd rom is not working how i can fix this problem
When i turn on cpu it is visible as a E drive, after insert any cd or dvd E-drive disappears every time happening with me, how my problem solve let me know