After a re-install of Photoshop CS4 Extended, because of problems with my iMac, it is impossible to give a preset size to the Crop Tool.How is that possible - and how can I repair that?
Did you trash the Photoshop's preferences before re-installing?
Reinstalling without trashing the preferences is futile, as you still have all the corruption there.
Quit Photoshop now and trash preferences:
Hold down Command, Option, and Shift keys while starting up Photoshop. A dialog box will appear asking if you wish to delete the preferences/settings file. Click on yes.