3520A reading problem on A7V8X-X

vbimport

#1

comp.1
a7v8x-x (bios rev. 1013, kt400a, vt8235), amd 1900, 512mb

comp.2
a7v8x-mx (bios rev. 1003, km400b, vt8235), amd 1600, 256mb

dvd: nec 3520a, 3.04 (nec.de)

No problems on comp.2, but it won’t read ANY dvd media on comp1. No problem with cdr/rw media on comp1. I suspect this is a bios or hardware problem (I have latest bios). I have checked ide cables and try all master/slave/cs combinations. When I put DVD in drive, comp. startup is slow (waits about 10-15 secs when checking boot records). Any idea?

Thx in advance.