If AppleShare users running on older Macintosh computers report these types of problems, check to see if TOPS has ever been in use in the environment. TOPS was a popular pre-System 7 way of setting up an ad-hoc network with distributed file sharing.
Unfortunately, when Apple finished AFP, TOPS was not compliant. Remnants of TOPS software left in the System Folder can cause Macintosh computers running System 7 to behave abnormally.
TOPS can be completely removed by two means only -- 'De-install' from the TOPS master installation diskette (unknowable results in System 7), or by a clean system install (preferred). This is because the TOPS installer put AFP non-compliant resources into the System file directly. Installing System 7 over the top of System 6 will not eliminate these resources, and the compatibility checker doesn't report them.
We have seen more than a few situations where TOPS was the culprit causing unexpected crashes of servers and workstations, inability to run File Sharing, or inability to use AppleShare once installed.