[QUOTE=chef;2114494]DMA problem still there, or a cable problem.[/QUOTE]
Chef - thanks for your help. I did already remove the upper and lower filters just as described and I did, I promise you, search the site as I always do on forums like this one.
Yesterday I sussed it. After trashing the registry on my work laptop trying to fix this, I rebuilt it from absolute zero. Still had the same problem, and found something strange with different versions of Nero’s InfoTool. Version 22.214.171.124 is the only one I have found that actually reports this drive’s rated maximum read speed of x24 - other versions report x4.
By accident I was looking in the Power Options to correct something else and I noticed in Advanced Settings, you can set the CD-ROM for “high performance”, “normal” or “silent”. Mine, of course, was set to “silent”. Set to “normal” and the problem’s solved. Checked the home laptop and, yes, that’s set to “normal”.
Why they would default to different settings during ground-up builds (I’ve done 'em both) I don’t know but there you are…