Sorry for my late response, I had two very busy days.
Maybe the following can help:
Try to delete the courses which have failed to restore completely (not the original courses or the backup files) in the courses overview.
If this doesn't help: Go to system administration > Development > Debugging and set it to "Developper".
See whether you get an error when you try to
upload a file.
In case you get any error, post it in the forum so that others can be of help.
It would be also useful to know what Moodle version you're using.
Hope any of this helps.