When I have a set of pictures, say Sandy1 I could open the file and highlight all images then drag the set to a folder on another disc and paste them all at one time. Now, I cal only paste one at a time into the new folder.
This happend after I updated to the lates version on by compuyter running 10.8.2.
Try this: launch iPhoto with the Option key held down and create a new, test library. Import enought photos to check to see if the same problem persists. If it doesn't then you current library is the culprit.
In that case make a temporary, backup copy of your library if you don't already have one (Control-click on the library and select Duplicate from the contextual menu) and apply the two fixes below in order as needed:
Launch iPhoto with the Command+Option keys held down and rebuild the library.
Since only one option can be run at a time start with Option #1, followed by #3 and then #4 as needed.
Using iPhoto Library Manager to Rebuild Your iPhoto Library
1 - download iPhoto Library Manager and launch.
2 - click on the Add Library button, navigate to your Home/Pictures folder and select your iPhoto Library folder.
3 - Now that the library is listed in the left hand pane of iPLM, click on your library and go to the File ➙ Rebuild Library menu option.
4 - In the next window name the new library and select the location you want it to be placed.
5 - Click on the Create button.
Note: This creates a new library based on the LIbraryData.xml file in the library and will recover Events, Albums, keywords, titles and comments. However, books, calendars, cards and slideshows will be lost. The original library will be left untouched for further attempts at fixing the problem or in case the rebuilt library is not satisfactory.
I tried your recomendations with no luck. I also spent 2 hrs at the Apple Store with 4 different Genius' with out any resolution. However, I can now use the export command to select groups of images to transfer. The selection of files with the mouse still is not working. Thank you very much for you comments. I don't know what to try next.