Thank you for your post.
Under the system requirements, we list the minimum CPU configuration for a PowerPC G5 as 2.0 GHz. Since you are only running 1.8 GHz, this may not install. You can see the system requirements on our web page directly at:
I also got an installer crash when I tried to install Filemaker Pro server 10 advanced on a G5 1.8Ghz iMac (2x80 Gb HD and 3.5 Gb RAM). But after installing Filemaker pro 10 advanced and a new effort to install FM Pro server the installation went on without any problem.