This may or may not be the cause of your particular problem, but System
6.0.2 is not compatible with the Macintosh IIcx. The minimum software
version is System 6.0.3, and we recommend running the System 6.0.5.
This problem sounds most like system software and/or driver corruption. We
suggest you do the following things:
1) Run the Find File desk accessory ensure you don't have multiple
System Folders on your hard drive
2) Regardless of how many System Folders you have, throw them all away
after saving copies of any third-party INITs or CDEVs that you haven't
backed up.
3) Use the Installer to install new System software and LaserWriter
drivers onto the hard drive. Make sure the operating system version is
at least 6.0.3.