Have recently upgraded to XP SP3 and hadn't read that you need to disable Alcohol and Daemon Tools before attempting. As expected got error message saying atapi.sys could not be backed up. Have checked all settings re autoplay function in Registry and all is as it should be. Problem I am having is that whilst the Bios and Windows can see the device nothing I put into the drive is recognised or autoplayed. I can't play, install or burn anything using the drive. I have since tried deleting Alcohol and Daemon tools and reinstalling XP service pack 3 and this all works with no errors and one assumes that the latest version of atapi.sys is also installed. However I still cannot read anything on any media I insert into the drive.
Anything else I can try before the dreaded rebuild/reinstall of XP. Machine seems to be working fine other than this one problem.