HP Pavilion PIII 850MHz, Creative DVD-RW, Nero Showtime problem

Hi all!
Just installed this Creative drive (DR8420E), and have had some problems. Drive is set to Master on the Secondary IDE channel, with original CD-RW drive set as slave. Intel Application Accelerator is installed (replaces Ultra-DMA) on the chipset. New drive would not read at all until I came upon the: Intel Application Accelerator User Guide (pdf). I found that limiting the transfer mode limit to UDMA-3 allowed immediate fix of reading problems, but while the drive will read data and burn anything, it will not allow for watching a DVD. This is the message I get when using Nero's Showtime: "Nero Showtime was unable to start playing the selected video. Please close all other applications that are playing back video or are in pause mode and try again." Note that there is no other such application in use. I have uninstalled Creative's PC/DVD player which I use with the matching drive and after registry clean and reboot found no change (no conflict). Checked for latest ASPI layer-OK
Since the new Creative DVD-RW comes with Nero (which I already had), I uninstalled and reinstalled to no avail.
I have use DVDXCopy to copy several DVDs perfectly using the new drive for reading and burning, so I am inclined to dismiss a hardware problem. I may try dropping the Accelerator another step. Any other ideas???? Fortunately, I can watch movies on the other Creative drive which has a nice hardware decoder card with TV outputs. No conflicts in Device Manager, no problem devices.

Have you tried uninstalling it and using the normal M$ drivers. If i remember correctly there are compatability issues with the drivers and some hardware.

I have uninstalled the Intel Application Accelerator- no change in the situation. Did a clean install of Windows - no change. I think there might be a conflict with DVDXCopy and ShowTime. I so, I'll live with it as I can play everything on the Creative PC/DVD using Creative's player. The new DVD-RW drive reads fine, and I can burn to it perfectly, just won't play DVD's.