Can't turn off auto arrange in Win XP

After installing a Western Digital external hard drive with Retrospect 6.5 software on Windows XP, I can't turn off autoarrange Desktop icons. (The usual solution: R->Desktop, ->Arrange Icons By, clear ___ Auto Arrange and __ Align to Grid doesn't work). Even with the auto arrange Desktop settings turned off, I get all icons lined up to the left of the screen, whenever I reboot. I couldn't find anything in Microsoft KB or with a google.com search of Web or groups.

Any suggestions? Is there a Registry setting for this?

Many thanks,
Timothy, in London.