--- a/InstrumentationContext.st	Sun Aug 21 12:33:50 2011 +0200
+++ b/InstrumentationContext.st	Sun Aug 21 13:29:22 2011 +0200
@@ -180,7 +180,9 @@
     "become the current instrumentaion context for a process."
 
     self class setInstrumentationContext:self in:aProcess.
-    CachedProcessToInstrumentationContextMapping removeKey:aProcess ifAbsent:[].
+    CachedProcessToInstrumentationContextMapping notNil ifTrue:[
+        CachedProcessToInstrumentationContextMapping removeKey:aProcess ifAbsent:[].
+    ].
 
     "
      InstrumentationContext new beActiveIn:(Processor activeProcess)
@@ -219,9 +221,9 @@
 !InstrumentationContext class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libcomp/InstrumentationContext.st,v 1.4 2011-08-21 10:33:50 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libcomp/InstrumentationContext.st,v 1.5 2011-08-21 11:29:22 cg Exp $'
 !
 
 version_CVS
-    ^ '$Header: /cvs/stx/stx/libcomp/InstrumentationContext.st,v 1.4 2011-08-21 10:33:50 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libcomp/InstrumentationContext.st,v 1.5 2011-08-21 11:29:22 cg Exp $'
 ! !