Thanks
My approach was as follows and it worked for me:
I uninstalled Acrobat 4.05 and PageMaker 7.01, and Adobe Type Manger Light, and Adobe Reader 6,01 before installing 6 Pro.
I also made sure that all versions of Distiller were removed.
The 6 Pro instructions caution that PageMaker 7 has to be installed after Acrobat 6 Pro and that the pre-v65 distiller that comes with the v7.0 PageMaker release must not be installed. I take this to imply that Acrobat 6 Pro prefers being the only Acrobat on the machine.
For all of the removed apps I deleted their folders as well AFTER rebooting following each uninstall.
Acrobat 6 Pro, which I installed from a store-bought upgrade CD, works flawlessly. However, I also installed the Pro 6.01 update before using the program.
Update to 6.0.1 and check for updated drivers too for the scanner.