Power Gallery Stopped Working

I have been using this application on the following web site for a number of months. My client has now loaded a number of images as he is a travel photographer.

I keep get a 500 internal server error, the host provider assures me that everything is alright at their end and that the my sql database is working correctly, so I am at a loss.

Could you help me. The website is www.nomadicmonkimages.com if you click to Wildlife on homepage then select a category say "Birds" the image gallery fails to load. If you need any more info pleas let me know.

I do have a backup of the database but would appreciate any assistance to restore procedure as i am not very confident in this area.

- I have received a comment from host provider who says that the database is fine the error is the timing out which suggests something else.

- I have uploaded a new database and site to test at www.sancere.com and am getting same issue - I only have 7 images on this site. If you click on Homepage "latest images" and this times out with a 500 internal sever error
Could you please help.