Sorry for the lack of updates, I am preparing Bullet 3.x initial release and get back to merging Bullet 2.x and Bullet 3.x afterwards.

fix some crash in btSoftBody, related to running out-of-memory. You can configure the default maximum memory allocation for the signed distance field using worldInfo->m_sparsesdf.Initialize(hash, maxAllocation);
fix 'exploding' btSoftBody, related to very small masses. You can configure maximum displacement per frame using worldInfo->m_maxDisplacement 
avoid some crash in the world importer

Extras/Serialize/BulletWorldImporter/btBulletWorldImporter.cpp

@@ -45,13 +45,14 @@ bool	btBulletWorldImporter::loadFile( const char* fileName, const char* preSwapF
 	bool result = loadFileFromMemory(bulletFile2);
 	//now you could save the file in 'native' format using
 	//bulletFile2->writeFile("native.bullet");
-	
-	if (preSwapFilenameOut)
+	if (result)
 	{
-		bulletFile2->preSwap();
-		bulletFile2->writeFile(preSwapFilenameOut);
+		if (preSwapFilenameOut)
+		{
+			bulletFile2->preSwap();
+			bulletFile2->writeFile(preSwapFilenameOut);
+		}
 	}
-
 	delete bulletFile2;
 	
 	return result;

src/BulletSoftBody/btSoftBody.cpp

@@ -1767,7 +1767,23 @@ void			btSoftBody::predictMotion(btScalar dt)
 	{
 		Node&	n=m_nodes[i];
 		n.m_q	=	n.m_x;
-		n.m_v	+=	n.m_f*n.m_im*m_sst.sdt;
+		btVector3 deltaV = n.m_f*n.m_im*m_sst.sdt;
+		{
+			btScalar maxDisplacement = m_worldInfo->m_maxDisplacement;
+			btScalar clampDeltaV = maxDisplacement/m_sst.sdt;
+			for (int c=0;c<3;c++)
+			{
+				if (deltaV[c]>clampDeltaV)
+				{
+					deltaV[c] = clampDeltaV;
+				}
+				if (deltaV[c]<-clampDeltaV)
+				{
+					deltaV[c]=-clampDeltaV;
+				}
+			}
+		}
+		n.m_v	+=	deltaV;
 		n.m_x	+=	n.m_v*m_sst.sdt;
 		n.m_f	=	btVector3(0,0,0);
 	}

src/BulletSoftBody/btSoftBody.h

@@ -45,6 +45,7 @@ struct	btSoftBodyWorldInfo
 	btScalar				air_density;
 	btScalar				water_density;
 	btScalar				water_offset;
+	btScalar				m_maxDisplacement;
 	btVector3				water_normal;
 	btBroadphaseInterface*	m_broadphase;
 	btDispatcher*	m_dispatcher;
@@ -55,6 +56,7 @@ struct	btSoftBodyWorldInfo
 		:air_density((btScalar)1.2),
 		water_density(0),
 		water_offset(0),
+		m_maxDisplacement(1000.f),//avoid soft body from 'exploding' so use some upper threshold of maximum motion that a node can travel per frame
 		water_normal(0,0,0),
 		m_broadphase(0),
 		m_dispatcher(0),

src/BulletSoftBody/btSparseSDF.h

@@ -69,6 +69,7 @@ struct	btSparseSdf
 	btScalar						voxelsz;
 	int								puid;
 	int								ncells;
+	int								m_clampCells;
 	int								nprobes;
 	int								nqueries;	
 
@@ -77,10 +78,13 @@ struct	btSparseSdf
 	//
 
 	//
-	void					Initialize(int hashsize=2383)
+	void					Initialize(int hashsize=2383, int clampCells = 256*1024)
 	{
+		//avoid a crash due to running out of memory, so clamp the maximum number of cells allocated
+		//if this limit is reached, the SDF is reset (at the cost of some performance during the reset)
+		m_clampCells = clampCells;
 		cells.resize(hashsize,0);
-		Reset();		
+		Reset();
 	}
 	//
 	void					Reset()
@@ -181,6 +185,15 @@ struct	btSparseSdf
 		{
 			++nprobes;		
 			++ncells;
+			int sz = sizeof(Cell);
+			if (ncells>m_clampCells)
+			{
+				static int numResets=0;
+				numResets++;
+//				printf("numResets=%d\n",numResets);
+				Reset();
+			}
+
 			c=new Cell();
 			c->next=root;root=c;
 			c->pclient=shape;