Well, first of all, that shouldn't happen.
I can't make it happen on a fresh install here, using built-in modules.
So, let's go step by step:
1. Delete the files from your server
2. Re-upload all the files to your server ... JUST the original Zen Cart files obtained from our site.
3. Log into your Admin
4. Go to Admin->Modules->Shipping
What do you see?
What happens if you click Install on one of the modules?
What happens if you click Edit?
5. Now upload the files for ONE of your addon modules.
Which module?
What happens when you go to Admin->Modules->Shipping ?
What happens if you click Install on the module?
6. Repeat for your other module.
What happens?




