Apple Logic Pro 9 - Manual (Page 315)

If you encounter problems with manually activated failed plug-ins, click the Disable Failed
Audio Units button in the Audio Units Manager window.
Warning: Use of plug-ins that have failed the validation can negatively affect the test
results of subsequently scanned plug-ins. They can also prevent Logic Pro from opening,
cause it to quit unexpectedly, or even lead to data loss (destroyed project files).
315 Chapter 10 Working with Instruments and Effects