Double check you're entering the correct serial, O can look like 0 late at night.

But you haven't got 2 Admin accounts have you? If so try an XP system restore in safe mode.

I had this exact situation and finally had to go back and restore the computer and reload the programs. Fortunately it's only used for editing and now no one else uses it either :( Save work first. Good luck.

Cheers.

"Double check you're entering the correct serial, O can look like 0 late at night.

But you haven't got 2 Admin accounts have you? If so try an XP system restore in safe mode. "

Thanks for your responses, but it can't be the serial number because I don't even get that far. This message appears immediately after I've doubleclicked the application's icon.
I do have multiple administrator accounts on my machine, since by default, because it's a home system, I set them all to have full administrator privileges.
I think there is something stuck in the registry somewhere. I'll have to have a dig through and see what I can clear out.

From my experience, DVD Architect doesn't like multiple administrator accounts, it only wants to see one on the computer you're trying to install it on.

I had 2 admin accounts and after 2 weeks of trying everything including Sony Help, once I did a full restore to one, DVD Architect 4.5 installed first time. HTH

Cheers.

I have three admin accounts on my comp (default admin, mine & wife's) & everything installs file. If the account was a user one @ one time maybe that is an issue.

Again, try the real admin account to see what happens.

I had the exact same problem but on a Vista machine. The only way I could run DVDA was by selecting the run with admin priviledges option. It was interseting in that other user accounts on the machine ran the program without this issue. i tried multiple solutions. I installed and reinstalled multiple times. I tried installing it using the Administrator account. I tried deleting registry entries and I also tried multiple solutions that were suggetested by Sony Technical Help - nothing worked. I lived with it for awhile but then I discovered that I could not render from Vegas Pro8 using Dolby Digital AC-3 Pro without the program asking me to purchase this option. Oddly if i ran Vegas Pro 8 from another user account on the same computer then I could use Dolby Digital Pro. Thus for some reason it was just this one user account where the program failed to register properly. My hunch is that this was some how realted to the fact that I had installed a trial version of DVDA on this account before I actually purchased the program. In the end the only way to solve it was to reinstall the operating system and then freshly install all my programs. It now works noramlly! What a pain!

In Vista, disable User Account Control. It's not needed in most situations and is almost impossible to get right. A very poorly thought-out feature in my opinion.

*shrug* I've always had multiple admin accounts on my PCs -- never had a problem installing, registering, or running DVDA because of it.

Rob

Disabling UAC allowed me to start DVDA without the system asking for permission but it did not solve the incomplete registration of the Dolby Digital AC-3 Pro plug-in. I really think Sony has a bug related to previous use of a trial version of the software.

I wouldn't necessarily take this error message literally.

I had the same error pop up it when trying to instal the last update, even though I was the sole user and administrator. Sony support told me to uninstal and reinstal everything with Sony in it, plus some Registry clearances.
I didn't want to spend half a day following "advice" I didn't believe, and eventually solved the problem by re-transferring the downloaded file from my internet machine - I didn't even have to re-download, just re-copy it onto a memory stick, and this time it installed perfectly.