Applications other than SmartSound: First of all, remember that SmartSound has no control of how other applications, (like PowerPoint, Media 100, Director etc.), play sound. If you are having trouble with sound in other applications, your might try exporting at a lower sample or bit rate to reduce the strain on your computer system. Also, check with the manual or tech support of the application in question.
SmartSound Quicktracks: Quicktracks relies on Apple's QuickTime to play sound. If playback is choppy, check your QuickTime Control Panel setting to make sure it's set to the optimum playback for your sound card.
SmartSound For Multimedia: If the playback is choppy or intermittent while inside SmartSound For Multimedia, the number one cause is... dust or fingerprints on the CD-ROM. Try cleaning the CD carefully with a soft cloth.
If that doesn't help, it may be that your CD-ROM drive or computer can't keep up to the data rate needed to play sound files directly from the CD. You can test that by going into the "Librarian..." from the Edit menu. Click on a library in the left box and click on a selection in the right box. Click the "Copy" button to copy that selection from the CD to your hard drive. Then go to the SmartSound Browser (from the File menu) and click on the selection you copied. Click the Play button and see if it plays correctly. If so, then either the CD is still dirty, or the CD drive can't keep up.