Index: /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumDetailsWidget.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumDetailsWidget.cpp	(revision 67946)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumDetailsWidget.cpp	(revision 67947)
@@ -524,6 +524,9 @@
 
     /* Load size: */
-    m_pLabelSize->setEnabled(m_newData.m_fValid && m_newData.m_enmType == UIMediumType_HardDisk);
-    m_pEditorSize->setEnabled(m_newData.m_fValid && m_newData.m_enmType == UIMediumType_HardDisk);
+    const bool fEnableResize =    m_newData.m_fValid
+                               && m_newData.m_enmType == UIMediumType_HardDisk
+                               && !(m_newData.m_enmVariant & KMediumVariant_Fixed);
+    m_pLabelSize->setEnabled(fEnableResize);
+    m_pEditorSize->setEnabled(fEnableResize);
     m_pEditorSize->setMediumSize(m_newData.m_options.m_uLogicalSize);
 }
Index: /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumDetailsWidget.h
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumDetailsWidget.h	(revision 67946)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumDetailsWidget.h	(revision 67947)
@@ -113,4 +113,5 @@
         : m_fValid(false)
         , m_enmType(UIMediumType_Invalid)
+        , m_enmVariant(KMediumVariant_Max)
         , m_options(UIDataMediumOptions())
         , m_details(UIDataMediumDetails())
@@ -121,4 +122,5 @@
         : m_fValid(false)
         , m_enmType(enmType)
+        , m_enmVariant(KMediumVariant_Max)
         , m_options(UIDataMediumOptions())
         , m_details(UIDataMediumDetails())
@@ -131,4 +133,5 @@
                && (m_fValid == other.m_fValid)
                && (m_enmType == other.m_enmType)
+               && (m_enmVariant == other.m_enmVariant)
                && (m_options == other.m_options)
                && (m_details == other.m_details)
@@ -145,4 +148,6 @@
     /** Holds the medium type. */
     UIMediumType m_enmType;
+    /** Holds the medium variant. */
+    KMediumVariant m_enmVariant;
 
     /** Holds the medium options. */
Index: /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumManager.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumManager.cpp	(revision 67946)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumManager.cpp	(revision 67947)
@@ -383,4 +383,5 @@
     m_fValid = !m_guiMedium.isNull();
     m_enmType = m_guiMedium.type();
+    m_enmVariant = m_guiMedium.mediumVariant();
     /* Gather medium options data: */
     m_options.m_enmType = m_guiMedium.mediumType();