Compressor 2 problem

Hello, I know Compressor 2 is ancient but I have it installed on a system with Mac OS 10.5.8.

It used to work (perhaps that was an older system) but now it crashes on startup.

I tried to install the 2.0.1 update but I get a message "You cannot install Compressor Update on this volume. 'Pro Application Update 2005-1' is required to install this software."

So I tried to install this update but then I got a message "You cannot install Pro Applications Update 2005-01 on this volume. Your computer does not need this update."

I do have DVD SP 4.1.2 installed on this volume.

Is there any chance I can get Compressor to work again?

TIA, Jan E.