New valgrind crash:

==1171== Invalid read of size 1
==1171==    at 0x402255E: strcmp (mc_replace_strmem.c:341)
==1171==    by 0x48717B3: g_str_equal (gstring.c:77)
==1171==    by 0x48489FE: g_hash_table_insert (ghash.c:240)
==1171==    by 0x4386F97: ensure_valid_themes (gtkicontheme.c:1133)
==1171==    by 0x438766F: gtk_icon_theme_lookup_icon (gtkicontheme.c:1268)
==1171==    by 0x807D3C9: panel_find_icon (panel-util.c:640)
==1171==    by 0x807D468: panel_load_icon (panel-util.c:668)
==1171==    by 0x806F46C: button_widget_reload_pixbuf (button-widget.c:187)
==1171==    by 0x806F515: button_widget_icon_theme_changed (button-widget.c:210)
==1171==    by 0x48049D8: g_cclosure_marshal_VOID__VOID (gmarshal.c:77)
==1171==    by 0x47F762A: g_closure_invoke (gclosure.c:490)
==1171==    by 0x4808102: signal_emit_unlocked_R (gsignal.c:2440)
==1171==    by 0x4809626: g_signal_emit_valist (gsignal.c:2199)
==1171==    by 0x48097E8: g_signal_emit (gsignal.c:2243)
==1171==    by 0x438629F: do_theme_change (gtkicontheme.c:624)
==1171==    by 0x4386AE4: gtk_icon_theme_rescan_if_needed (gtkicontheme.c:1725)
==1171==    by 0x4386EDD: ensure_valid_themes (gtkicontheme.c:1192)
==1171==    by 0x438766F: gtk_icon_theme_lookup_icon (gtkicontheme.c:1268)
==1171==    by 0x807D3C9: panel_find_icon (panel-util.c:640)
==1171==    by 0x807D468: panel_load_icon (panel-util.c:668)
==1171==    by 0x806F46C: button_widget_reload_pixbuf (button-widget.c:187)
==1171==    by 0x806F515: button_widget_icon_theme_changed (button-widget.c:210)
==1171==    by 0x48049D8: g_cclosure_marshal_VOID__VOID (gmarshal.c:77)
==1171==    by 0x47F770C: g_closure_invoke (gclosure.c:490)
==1171==    by 0x4808102: signal_emit_unlocked_R (gsignal.c:2440)
==1171==    by 0x4809626: g_signal_emit_valist (gsignal.c:2199)
==1171==    by 0x48097E8: g_signal_emit (gsignal.c:2243)
==1171==    by 0x438629F: do_theme_change (gtkicontheme.c:624)
==1171==    by 0x4386AE4: gtk_icon_theme_rescan_if_needed (gtkicontheme.c:1725)
==1171==    by 0x4386EDD: ensure_valid_themes (gtkicontheme.c:1192)
==1171==    by 0x438766F: gtk_icon_theme_lookup_icon (gtkicontheme.c:1268)
==1171==    by 0x807D3C9: panel_find_icon (panel-util.c:640)
==1171==    by 0x807D468: panel_load_icon (panel-util.c:668)
==1171==    by 0x806F46C: button_widget_reload_pixbuf (button-widget.c:187)
==1171==    by 0x806F515: button_widget_icon_theme_changed (button-widget.c:210)
==1171==    by 0x48049D8: g_cclosure_marshal_VOID__VOID (gmarshal.c:77)
==1171==    by 0x47F762A: g_closure_invoke (gclosure.c:490)
==1171==    by 0x4808102: signal_emit_unlocked_R (gsignal.c:2440)
==1171==    by 0x4809626: g_signal_emit_valist (gsignal.c:2199)
==1171==    by 0x48097E8: g_signal_emit (gsignal.c:2243)
==1171==  Address 0x7415230 is 0 bytes inside a block of size 7 free'd
==1171==    at 0x402123A: free (vg_replace_malloc.c:233)
==1171==    by 0x485C130: g_free (gmem.c:187)
==1171==    by 0x4848910: g_hash_table_replace (ghash.c:390)
==1171==    by 0x4385373: insert_theme (gtkicontheme.c:2219)
==1171==    by 0x438515A: insert_theme (gtkicontheme.c:995)
==1171==    by 0x438515A: insert_theme (gtkicontheme.c:995)
==1171==    by 0x438515A: insert_theme (gtkicontheme.c:995)
==1171==    by 0x438515A: insert_theme (gtkicontheme.c:995)
==1171==    by 0x4386BCE: ensure_valid_themes (gtkicontheme.c:1045)
==1171==    by 0x438766F: gtk_icon_theme_lookup_icon (gtkicontheme.c:1268)
==1171==    by 0x807D3C9: panel_find_icon (panel-util.c:640)
==1171==    by 0x807D468: panel_load_icon (panel-util.c:668)
==1171==    by 0x806F46C: button_widget_reload_pixbuf (button-widget.c:187)
==1171==    by 0x806F515: button_widget_icon_theme_changed (button-widget.c:210)
==1171==    by 0x48049D8: g_cclosure_marshal_VOID__VOID (gmarshal.c:77)
==1171==    by 0x47F762A: g_closure_invoke (gclosure.c:490)
==1171==    by 0x4808102: signal_emit_unlocked_R (gsignal.c:2440)
==1171==    by 0x4809626: g_signal_emit_valist (gsignal.c:2199)
==1171==    by 0x48097E8: g_signal_emit (gsignal.c:2243)
==1171==    by 0x438629F: do_theme_change (gtkicontheme.c:624)
==1171==    by 0x4386AE4: gtk_icon_theme_rescan_if_needed (gtkicontheme.c:1725)
==1171==    by 0x4386EDD: ensure_valid_themes (gtkicontheme.c:1192)
==1171==    by 0x438766F: gtk_icon_theme_lookup_icon (gtkicontheme.c:1268)
==1171==    by 0x807D3C9: panel_find_icon (panel-util.c:640)
==1171==    by 0x807D468: panel_load_icon (panel-util.c:668)
==1171==    by 0x806F46C: button_widget_reload_pixbuf (button-widget.c:187)
==1171==    by 0x806F515: button_widget_icon_theme_changed (button-widget.c:210)
==1171==    by 0x48049D8: g_cclosure_marshal_VOID__VOID (gmarshal.c:77)
==1171==    by 0x47F770C: g_closure_invoke (gclosure.c:490)
==1171==    by 0x4808102: signal_emit_unlocked_R (gsignal.c:2440)
==1171==    by 0x4809626: g_signal_emit_valist (gsignal.c:2199)
==1171==    by 0x48097E8: g_signal_emit (gsignal.c:2243)
==1171==    by 0x438629F: do_theme_change (gtkicontheme.c:624)
==1171==    by 0x4386AE4: gtk_icon_theme_rescan_if_needed (gtkicontheme.c:1725)
==1171==    by 0x4386EDD: ensure_valid_themes (gtkicontheme.c:1192)
==1171==    by 0x438766F: gtk_icon_theme_lookup_icon (gtkicontheme.c:1268)
==1171==    by 0x807D3C9: panel_find_icon (panel-util.c:640)
==1171==    by 0x807D468: panel_load_icon (panel-util.c:668)
==1171==    by 0x806F46C: button_widget_reload_pixbuf (button-widget.c:187)
==1171==    by 0x806F515: button_widget_icon_theme_changed (button-widget.c:210)