Summary
Adobe PDF IFilter 6.0 is not compatible with Laserfiche, and may cause Laserfiche to crash when you attempt to close it. This issue is not present when using Adobe PDF IFilter 5.0.
Resolution
Install Adobe PDF IFilter 5.0 to extract text from PDFs. Version 5.0 can be obtained from the Adobe website:
If you have installed versions 6 or 7 of Adobe Acrobat or Reader, Adobe PDF IFilter 6.0 will automatically be installed. In order to return to Adobe PDF IFilter 5.0, you will need to re-install that version from the link above.