Q: Photostream - error occurred while joining the Photo Stream

Hi newMacUser09,

Welcome to the Support Communities!

The first thing I'd like to address for you is the issue that the photos in the photostream are different on different devices.  Here's how to "reset" it.

iCloud: My Photo Stream troubleshooting

http://support.apple.com/kb/TS3989

I see different photos in My Photo Stream on each of my devices.

Your device will keep up to 1000 photos, even if they are older than 30 days. Photos older than 30 days are removed from the iCloud server, so all devices may not have the same photos, depending on when you enabled My Photo Stream.

If you prefer to have only the most current photos in My Photo Stream on each of your devices, and delete the older photos:

• If there are any photos in My Photo Stream that you want to keep, save them to your Camera Roll, then back up your Camera Roll and other data using iCloud or iTunes.
• Turn My Photo Stream off in Settings > iCloud > Photos (on a device using iOS 6, go to Settings > iCloud > Photo Stream). Confirm that you wish to Delete Photos.
• Turn My Photo Stream back on. iCloud will automatically push your stored photos to your device.
• Repeat these steps for each device.

Regarding your shared photo stream, the articles below may be helpful:

iCloud: Troubleshooting iCloud Photo Sharing and Shared Photo Streams

http://support.apple.com/kb/TS4379

Manage subscribers to your shared streams - iCloud Help

http://help.apple.com/icloud/#/mmc0cd7bfa

I hope this information helps ....

Happy Holidays!

- Judy