Matshita UJDA-720 not reading DVDs (goes to sleep?)

i have strange problem with my UJDA 720 on fujitsu siemens Amilo D - if I put in home burned DVD, i manage to access it with no problems and if I try to copy/work with the disc, its fine. but as long as i leave it for about 4mins, its just does not manage to find the disc and applications are just freezing, 'coz they are waiting for data from the disc. there is no sound that the reader would turn or something, looks like it goes to sleep or just does not manage to re-load contents of the DVD or what. I tried both DVD-R and DVD+R discs, result is the same. CDs work as they should… any idea what could be possibly wrong? Am using Windows XP Pro + service pack 2 as system.

Thanks a lot,

Try factory DVDs. Could be bad burn or bad media.

i dont think its the way media are budned, i tried different DVD discs and different ways of burning them but none works.
Maybe an firmware update needed? Noone had simular problem to this…?