Sunshine Photo Cart Error Code

Hi,

for the past couple of weeks I have been getting this error code:
Warning: unserialize() expects parameter 1 to be string, array given in /home3/amygriffiths/public_html/wp-content/plugins/sunshine-photo-cart/admin/sunshine-dashboard.php on line 137

This shows up in the sunshine photo cart overview widget in my dashboard, and repeats itself 10 times.
This does often show up at the top of a page at the back end as well.

Please can you advise on a fix?

Dan