If they worked once and don't now then it is something that was done in the intervening period. This can include... but is not limited to ... installation of other software, directly or indirectly related to arcmap... a bad user profile (you can reset your application profile) ... a specific project doesn't work but others do... other users have no problem on your machine, but you do...
So can you fill in some of those blanks in what you tried and have ruled out?
This is my first time running a geoprocessing tool, so this I have not had it work properly before.
Originally I was receiving an ActiveX error when attempting to run a tool. I managed to fix this error by going into my privacy settings in Internet explorer. The error went away, but now using a tool causes the program to freeze.
Problem persists with all other projects.
I am the only user on my machine.
I haven't downloaded any other software recently before installing ArcMap or after.