Dear Jackie,
I am not sure I understand your exact problem details, but this may be a known and solvable issue with Safari.
Relatively recent versions of Safari now have a default setting of running Silverlight in 'Sandbox' mode. This mode protects the user by restricting plugins such as Silverllight from doing certain things that can include allowing it access to your file system to upload files. You can adjust this setting in Safari's Preferences to take Silverlight out of Sandbox mode.
If you go to Safari preferences, Security and click on Manage Website Settings you can then select Silverlight and tell it to 'Allow' Silverlight to run in, what they are calling, unsafe mode. In the past Silverlight was allowed, by default, to run in this mode but at some point Apple changed this setting. Making this change should allow you to upload your files (you will need to restart Safari after making this change). Firefox does not suffer from this at all.
If the above doesn't apply to you, please come back to us with more details, I will need to know the exact procedure you are following, with a description of what goes wrong. The more details, the better. It is also possible that you are experiencing a problem with the particular file you are trying to upload, if that's the case, you may want to send us the file to "Eppisupport@ioe.ac.uk" including the review details, and an indication of what item should receive the given file (please indicate the item ID).
I hope this helps,
Sergio