My computer has an ASUS A7V board, AMD Athlon 1200 MHZ processor and running Windows ME. The hard drives are on the ATA-100 controller, the primary master is a CD ROM and the primary slave is a CD RW. The secondary master is a LS-120 drive. Both CD's are set to mode 4. The problem, about eighty percent of the time I boot up the post does not recognize the primary slave CD. However, even though it is not recognized this drive is still usable and is in the line-up after boot up. I have tried swapping the two CD drives but get the same results, the secondary is seldom recognized. This is really just an annoyance, but I am tired of pressing the F1 key. Any ideas?

I'm sure you have checked their jumper settings as master and slave, if the other one was not recognized during windows bootup? then look into device manager and check the cd-rw if there's yellow exclamation sign there, try to reload its driver. If it happened that there's no cd-rw detected then maybe its the ide cable. try replacing it with a new one.Goodluck!!

Some CD-RWs do not like to be a slave with another cd device. Also, it is preferable for cdroms and cd burners to NOT be on the same IDE port - different ports helps to prevent buffer underruns. How about rearranging the devices, and see if things change. Primary Master = CDRW Secondary Master = ZIP Secondary Slave = CDROM

Krystyna your suggestion, along with making a BIOS change on both CD drives to "Auto" fixed the problem. Thanks to all who helped.