but installing the FS9.1 update stops on AI_PLAYR.DLL and says the update can't be installed, any suggestions please?.
You probably have a mix-match of versions. Some files might be 9.0 other 9.1 already, so the FS9.1 patch gets confused.
You can try to restore all the original FS9.0 DLL (and the 9.0 FS9.EXE) be grabbing them from your FS9 CD, they are inside the .CAB files, which can be opened with most of unzipping utilities, like WinRar.
After you restore all the original DLL/EXE from the FS9.0 CD, you can apply the 9.1 patch again, and it should probably work.