If you have over 150 fonts installed, it's highly recommended that you use an external font manager (such as ATM Deluxe) to handle them in custom small sets that can be activated and deactivated as needed. If you uninstall fonts, be sure to not uninstall any required fonts (list available if needed) for the operating system you are using or you're likely to have other problems.
Bob
For more specific suggestions it might be wise to give the *exact versions* of Illustrator, PhotoShop and ATM or whatever "font manager program" you refer to. Any correctly installed fonts should show up in all applications -- but as Bob has pointed out, sometimes one corrupt font or too many, or poor quality fonts can tumble the whole process.