I'm not aware of any software called Adobe Photoshop Assistant. Could you post a link to the page your're trying to download from.
If you're trying to download PS6, you can do that from the following page: http://www.adobe.com/cfusion/tdrc/index.cfm?product=photoshop&loc=en_u s
If you face any errors, please post the details so that folks here can help you troubleshoot.
Europe, Middle East and Africa