File system error when opening a member

I'm receiving a dialog box for RSEF1002E: 'Operation failed.  File system 
input or output error' when I try to open source members from certain 
source files.  The .log file shows:

!ENTRY com.ibm.etools.systems.core 4 0 Sep 08, 2004 15:35:28.550
!MESSAGE Error when opening member
!STACK 0
java.lang.ClassCastException: 
com/ibm/etools/iseries/core/api/ISeriesObject incompatible with 
com/ibm/etools/iseries/core/api/ISeriesFile
        at java.lang.Throwable.<init>(Throwable.java)
        at java.lang.Throwable.<init>(Throwable.java:66)
        at java.lang.ClassCastException.<init>(ClassCastException.java:56)
        at 
com.ibm.etools.iseries.core.api.ISeriesMember.getISeriesFile(Unknown 
Source)
        at 
com.ibm.etools.iseries.core.resources.ISeriesEditableSrcPhysicalFileMember.open(Unknown
 
Source)

                              .                              .       .

                              .                              .       .

                              .                              .       .

        at org.eclipse.core.launcher.Main.run(Main.java:747)
        at org.eclipse.core.launcher.Main.main(Main.java:583)
!ENTRY com.ibm.etools.systems.core 4 0 Sep 08, 2004 15:35:30.207
!MESSAGE RSEF1002E: SUB#0:com/ibm/etools/iseries/core/api/ISeriesObject 
incompatible with com/ibm/etools/iseries/core/api/ISeriesFile

If the rest of the log file entries would help I can send them, but I 
would rather keep the post to this list smaller.

Thanks in advance for any help!