If you are using an external CD-rom, the SCSI-chain should be terminated on the internal scsi-chain, after the harddrive, have no termination on the motherboard itself (as it then is in the middle of the scsi-chain) and be terminated on the external scsi-chain after the CD-ROM.
At what IDs have you set your HD and CD-ROM?
Also do a search for "Specific Troublesome Devices" on
this page and see if any of these issues applies to your A3000. There are also some good termination guidelines and examples there.
/Patrik
