With Garbage Collector enabled you will get the following exception while
starting up:

!SESSION ----------------------------------------------------------------------
!ENTRY org.eclipse.core.launcher 4 0 Dec 22, 2002 16:44:54.530
!MESSAGE Exception launching the Eclipse Platform:
!STACK
java.lang.reflect.InvocationTargetException
   at _Jv_CallAnyMethodA(java.lang.Object, java.lang.Class, _Jv_Method, boolean, java.lang.Class[], jvalue, jvalue) (/usr/local/gcc34/lib/libgcj.so.4.0.0)
   at _Jv_CallAnyMethodA(java.lang.Object, java.lang.Class, _Jv_Method, boolean, java.lang.Class[], java.lang.Object[]) (/usr/local/gcc34/lib/libgcj.so.4.0.0)
   at java.lang.reflect.Method.invoke(java.lang.Object, java.lang.Object[]) (/usr/local/gcc34/lib/libgcj.so.4.0.0)
   at org.eclipse.core.launcher.Main.basicRun(java.lang.String[]) (Unknown Source)
   at org.eclipse.core.launcher.Main.run(java.lang.String[]) (Unknown Source)
   at org.eclipse.core.launcher.Main.main(java.lang.String[]) (Unknown Source)
Caused by: java.lang.NullPointerException
   at java.lang.String.getBytes() (/usr/local/gcc34/lib/libgcj.so.4.0.0)
   at org.eclipse.core.internal.boot.InternalBootLoader.decode(java.lang.String) (Unknown Source)
   at org.eclipse.core.internal.boot.PlatformConfiguration.getRuntimeImport() (Unknown Source)
   at org.eclipse.core.internal.boot.PlatformConfiguration.locateDefaultPlugins() (Unknown Source)
   at org.eclipse.core.internal.boot.PlatformConfiguration.PlatformConfiguration(java.lang.String, java.lang.String, java.net.URL) (Unknown Source)
   at org.eclipse.core.internal.boot.PlatformConfiguration.startup(java.lang.String[], java.net.URL, java.lang.String, java.lang.String) (Unknown Source)
   at org.eclipse.core.internal.boot.InternalBootLoader.initialize(java.net.URL, java.lang.String, java.lang.String[]) (Unknown Source)
   at org.eclipse.core.internal.boot.InternalBootLoader.startup(java.net.URL, java.lang.String, java.lang.String[], java.lang.Runnable) (Unknown Source)
   at org.eclipse.core.internal.boot.InternalBootLoader.run(java.lang.String, java.net.URL, java.lang.String, java.lang.String[], java.lang.Runnable) (Unknown Source)
   at org.eclipse.core.boot.BootLoader.run(java.lang.String, java.net.URL, java.lang.String, java.lang.String[], java.lang.Runnable) (Unknown Source)
   at _Jv_CallAnyMethodA(java.lang.Object, java.lang.Class, _Jv_Method, boolean, java.lang.Class[], jvalue, jvalue) (/usr/local/gcc34/lib/libgcj.so.4.0.0)
   ...5 more

To disable the garbage collector do:
export GC_DONT_GC=1

Restarting eclipse will give the following errors and your library/classpath
settings will be
[Fatal Error] :1:15: The value following "version" in the XML declaration must be a quoted string.
[Fatal Error] :1:15: The value following "version" in the XML declaration must be a quoted string.
[Fatal Error] :1:15: The value following "version" in the XML declaration must be a quoted string.
[Fatal Error] :1:1: Content is not allowed in prolog.


While deleting files:
Exception in org.eclipse.ui.actions.DeleteResourceAction.run: java.lang.IllegalMonitorStateException: current thread not owner

Sometimes the
#0  0x40862ce2 in sigsuspend () from /lib/libc.so.6
#1  0x407e96df in __pthread_wait_for_restart_signal ()
   from /lib/libpthread.so.0
#2  0x407e6173 in pthread_cond_wait () from /lib/libpthread.so.0
#3  0x403782b8 in _Jv_CondWait(_Jv_ConditionVariable_t*, _Jv_Mutex_t*, long long, int) (cv=0x38df8b3c, mu=0x38df8b40, millis=0, nanos=0)
    at ../../../gcc/libjava/posix-threads.cc:143
#4  0x4039e0d3 in _Jv_MonitorEnter (obj=0x38cfa150)
    at ../../../gcc/libjava/java/lang/natObject.cc:845
#5  0x403997af in java::lang::Class::initializeClass() (this=0x38cfa150)
    at ../../../gcc/libjava/java/lang/natClass.cc:742
#6  0x40387b6b in _Jv_ResolvePoolEntry(java::lang::Class*, int) (
    klass=0x38cfa230, index=43) at ../../../gcc/libjava/java/lang/Class.h:265