diff --git a/mozilla/htmlparser/src/CNavDTD.cpp b/mozilla/htmlparser/src/CNavDTD.cpp
index 28409508a84..15ca7ced182 100644
--- a/mozilla/htmlparser/src/CNavDTD.cpp
+++ b/mozilla/htmlparser/src/CNavDTD.cpp
@@ -1245,11 +1245,17 @@ nsresult CNavDTD::WillHandleStartTag(CToken* aToken,eHTMLTags aTag,nsCParserNode
      *
      * Now a little code to deal with bug #49687 (crash when layout stack gets too deep)
      * I've also opened this up to any container (not just inlines): re bug 55095
+     * Improved to handle bug 55980 (infinite loop caused when DEPTH is exceeded and
+     * </P> is encountered by itself (<P>) is continuously produced.
      *
      **************************************************************************************/
-
+ 
   if(MAX_REFLOW_DEPTH<mBodyContext->GetCount()) {
-    return kHierarchyTooDeep;  
+    if(nsHTMLElement::IsContainer(aTag)) {
+      if(!gHTMLElements[aTag].HasSpecialProperty(kHandleStrayTag)) {
+        return kHierarchyTooDeep; //drop the container on the floor.
+      }        
+    }
   }
 
   STOP_TIMER()
@@ -2369,6 +2375,7 @@ nsresult CNavDTD::CollectSkippedContent(nsCParserNode& aNode,PRInt32 &aCount) {
  *  @return  PR_TRUE if parent can contain child
  */
 PRBool CNavDTD::CanContain(PRInt32 aParent,PRInt32 aChild) const {
+    
   PRBool result=gHTMLElements[aParent].CanContain((eHTMLTags)aChild);
 
 #ifdef ALLOW_TR_AS_CHILD_OF_TABLE
@@ -2390,6 +2397,14 @@ PRBool CNavDTD::CanContain(PRInt32 aParent,PRInt32 aChild) const {
     }
   }
 
+  if(eHTMLTag_nobr==aChild) {
+    if(IsInlineElement(aParent,aParent)){
+      if(HasOpenContainer((eHTMLTags)aChild)) {
+        return PR_FALSE;
+      }
+    }
+  }
+
   return result;
 } 
 
diff --git a/mozilla/htmlparser/src/nsElementTable.cpp b/mozilla/htmlparser/src/nsElementTable.cpp
index 98d9d92fc63..f9d081bf74f 100644
--- a/mozilla/htmlparser/src/nsElementTable.cpp
+++ b/mozilla/htmlparser/src/nsElementTable.cpp
@@ -2025,6 +2025,20 @@ eHTMLTags nsHTMLElement::GetCloseTargetForEndTag(nsDTDContext& aContext,PRInt32
     }
     
   }
+
+  else if(gHTMLElements[mTagID].IsTableElement()) {
+    
+      //This fixes 57378...
+      //example: <TABLE><THEAD><TR><TH></THEAD> which didn't close the <THEAD>
+
+    PRInt32 theLastTable=aContext.LastOf(eHTMLTag_table);
+    PRInt32 theLastOfMe=aContext.LastOf(mTagID);
+    if(theLastTable<theLastOfMe) {
+      return mTagID;
+    }
+        
+  }
+
   return result;
 }
 
diff --git a/mozilla/htmlparser/src/nsElementTable.h b/mozilla/htmlparser/src/nsElementTable.h
index 492a75db3fb..23e16a3675c 100644
--- a/mozilla/htmlparser/src/nsElementTable.h
+++ b/mozilla/htmlparser/src/nsElementTable.h
@@ -147,6 +147,28 @@ struct nsHTMLElement {
                     return PR_FALSE;
                   }
 
+  inline  PRBool  IsTableElement(void) {  //return yes if it's a table or child of a table...
+                    PRBool result=PR_FALSE;
+
+                    switch(mTagID) {
+                      case eHTMLTag_table:
+                      case eHTMLTag_thead:
+                      case eHTMLTag_tbody:
+                      case eHTMLTag_tfoot:
+                      case eHTMLTag_caption:
+                      case eHTMLTag_tr:
+                      case eHTMLTag_td:
+                      case eHTMLTag_th:
+                      case eHTMLTag_col:
+                      case eHTMLTag_colgroup:
+                        result=PR_TRUE;
+                        break;
+                      default:
+                        result=PR_FALSE;
+                    }
+                    return result;
+                  }
+
   static  int     GetSynonymousGroups(eHTMLTags aTag);
 
 
diff --git a/mozilla/parser/htmlparser/src/CNavDTD.cpp b/mozilla/parser/htmlparser/src/CNavDTD.cpp
index 28409508a84..15ca7ced182 100644
--- a/mozilla/parser/htmlparser/src/CNavDTD.cpp
+++ b/mozilla/parser/htmlparser/src/CNavDTD.cpp
@@ -1245,11 +1245,17 @@ nsresult CNavDTD::WillHandleStartTag(CToken* aToken,eHTMLTags aTag,nsCParserNode
      *
      * Now a little code to deal with bug #49687 (crash when layout stack gets too deep)
      * I've also opened this up to any container (not just inlines): re bug 55095
+     * Improved to handle bug 55980 (infinite loop caused when DEPTH is exceeded and
+     * </P> is encountered by itself (<P>) is continuously produced.
      *
      **************************************************************************************/
-
+ 
   if(MAX_REFLOW_DEPTH<mBodyContext->GetCount()) {
-    return kHierarchyTooDeep;  
+    if(nsHTMLElement::IsContainer(aTag)) {
+      if(!gHTMLElements[aTag].HasSpecialProperty(kHandleStrayTag)) {
+        return kHierarchyTooDeep; //drop the container on the floor.
+      }        
+    }
   }
 
   STOP_TIMER()
@@ -2369,6 +2375,7 @@ nsresult CNavDTD::CollectSkippedContent(nsCParserNode& aNode,PRInt32 &aCount) {
  *  @return  PR_TRUE if parent can contain child
  */
 PRBool CNavDTD::CanContain(PRInt32 aParent,PRInt32 aChild) const {
+    
   PRBool result=gHTMLElements[aParent].CanContain((eHTMLTags)aChild);
 
 #ifdef ALLOW_TR_AS_CHILD_OF_TABLE
@@ -2390,6 +2397,14 @@ PRBool CNavDTD::CanContain(PRInt32 aParent,PRInt32 aChild) const {
     }
   }
 
+  if(eHTMLTag_nobr==aChild) {
+    if(IsInlineElement(aParent,aParent)){
+      if(HasOpenContainer((eHTMLTags)aChild)) {
+        return PR_FALSE;
+      }
+    }
+  }
+
   return result;
 } 
 
diff --git a/mozilla/parser/htmlparser/src/nsElementTable.cpp b/mozilla/parser/htmlparser/src/nsElementTable.cpp
index 98d9d92fc63..f9d081bf74f 100644
--- a/mozilla/parser/htmlparser/src/nsElementTable.cpp
+++ b/mozilla/parser/htmlparser/src/nsElementTable.cpp
@@ -2025,6 +2025,20 @@ eHTMLTags nsHTMLElement::GetCloseTargetForEndTag(nsDTDContext& aContext,PRInt32
     }
     
   }
+
+  else if(gHTMLElements[mTagID].IsTableElement()) {
+    
+      //This fixes 57378...
+      //example: <TABLE><THEAD><TR><TH></THEAD> which didn't close the <THEAD>
+
+    PRInt32 theLastTable=aContext.LastOf(eHTMLTag_table);
+    PRInt32 theLastOfMe=aContext.LastOf(mTagID);
+    if(theLastTable<theLastOfMe) {
+      return mTagID;
+    }
+        
+  }
+
   return result;
 }
 
diff --git a/mozilla/parser/htmlparser/src/nsElementTable.h b/mozilla/parser/htmlparser/src/nsElementTable.h
index 492a75db3fb..23e16a3675c 100644
--- a/mozilla/parser/htmlparser/src/nsElementTable.h
+++ b/mozilla/parser/htmlparser/src/nsElementTable.h
@@ -147,6 +147,28 @@ struct nsHTMLElement {
                     return PR_FALSE;
                   }
 
+  inline  PRBool  IsTableElement(void) {  //return yes if it's a table or child of a table...
+                    PRBool result=PR_FALSE;
+
+                    switch(mTagID) {
+                      case eHTMLTag_table:
+                      case eHTMLTag_thead:
+                      case eHTMLTag_tbody:
+                      case eHTMLTag_tfoot:
+                      case eHTMLTag_caption:
+                      case eHTMLTag_tr:
+                      case eHTMLTag_td:
+                      case eHTMLTag_th:
+                      case eHTMLTag_col:
+                      case eHTMLTag_colgroup:
+                        result=PR_TRUE;
+                        break;
+                      default:
+                        result=PR_FALSE;
+                    }
+                    return result;
+                  }
+
   static  int     GetSynonymousGroups(eHTMLTags aTag);