2 LG burners don't work at the same time

Hi,
I just joined this forum and hope someone out there can help me. I bought 2 LG Combo DVD writers - one is GSA-4082B (last year) and the other is GSA-2164D USB (a few days old). When I fixed in the new DVD writer, the old writer was detected but can’t read any CDs or DVDs that I put in. The new writer works fine. When I remove the new writer, the old writer remains dead. I uninstalled all the DVD drivers and let it autodetect and then the old writer works but dies off after I reboot the PC. I’m going nuts over this. I tried asking LG but no reply. Help…