There is one option in the Twonky config page that may help. Find out the IP address of the Linkstation, and then try this.
1. Go to the Twonky configuration page:
http://<ip_of_linkstation>:9050/
Example:
http://192.168.11.150:9050/
2. Click on TwonkyMedia Settings, then on the left under Advanced Setup, click on Miscellaneous.
3. Check the box for Disable Photo Rescaling.
4. Click Save Changes at the top, then after it's done saving, Restart Server.
PLEASE someone try this and let me know how it works out. If this is the solution, I'll pass the info on to our devs so we can set that option to be checked by default in future firmware versions.
Also, it appears that Twonky might have issues with photos 12 megapixels and up, so try the above procedure first, if that doesn't help, scale the photos down about halfway in resolution, and see what happens.