When you apply a slide transition to a group of slides in slide sorter view, PowerPoint appears to stop responding, or it takes a long time to redraw the screen.

This behavior occurs when the AutoPreview setting is turned on when you are applying a transition to a large number of slides. The transition is applied to each and every selected slide, and then an animated preview of the transition is shown for each slide that the transition was applied to.

To resolve this issue, turn off AutoPreview. To do this, follow these steps:

1. If the Slide Transition pane is not visible, click Slide Transition on the Slide Show menu.
2. Click to clear the AutoPreview check box (in the lower left corner of the Slide Transition pane).

NOTE: Turning off AutoPreview reduces the refresh time, but you will not be able to see what the selected transitions do.

To work around this issue, use either of the following methods.

Method 1: Apply Transitions on the Outline Tab

1. On the View menu, click Normal.
2. On the Outline tab of the left pane, click the slide icon for the first slide in the group.
3. To select more slides, do either of the following steps:
   
   
   • Hold down the SHIFT key and select a contiguous range of slides.
     -or-
     
   • On the Edit menu, click Select All.
4. On the Slide Show menu, click Slide Transitions.
5. Select any transition in the Apply to selected slides list.

NOTE: Only the slide in the Slide Pane will preview the transition effect.

Method 2: Apply Transitions on the Slides Tab

1. On the View menu, click Normal.
2. Under the Slides tab of the left hand pane, click on the slide miniature for the first slide in the group.
3. To select more slides, either:
   Hold down the SHIFT key, then click to select a contiguous range of slides.
   -OR-
   
   Hold down the CTRL key, then click to select a discontinuous range of slides.
   -OR-
   From the Edit menu, click Select All.
4. On the Slide Show menu, click Slide Transitions.
5. Select any transition from the Apply to selected slides list.