ODE INTERNAL ERROR 1: assertion "(nMinX < nMaxX) || (nMinZ < nMaxZ)" failed in dCollideHeightfield() [heightfield.cpp]
Stacktrace:

  at (wrapper managed-to-native) Ode.NET.d.Collide (intptr,intptr,int,Ode.NET.d/ContactGeom[],int) <0x00004>
  at (wrapper managed-to-native) Ode.NET.d.Collide (intptr,intptr,int,Ode.NET.d/ContactGeom[],int) <0xffffffff>
  at OpenSim.Region.Physics.OdePlugin.OdeScene.near (intptr,intptr,intptr) <0x000a9>
  at (wrapper native-to-managed) OpenSim.Region.Physics.OdePlugin.OdeScene.near (intptr,intptr,intptr) <0xffffffff>
  at (wrapper managed-to-native) Ode.NET.d.SpaceCollide2 (intptr,intptr,intptr,Ode.NET.d/NearCallback) <0x00004>
  at (wrapper managed-to-native) Ode.NET.d.SpaceCollide2 (intptr,intptr,intptr,Ode.NET.d/NearCallback) <0xffffffff>
  at OpenSim.Region.Physics.OdePlugin.OdeScene.collision_optimized () <0x000f8>
  at OpenSim.Region.Physics.OdePlugin.OdeScene.Simulate (single) <0x0076f>
  at OpenSim.Region.Environment.Scenes.Scene.UpdatePhysics (double) <0x00038>
  at OpenSim.Region.Environment.Scenes.Scene.Update () <0x0019a>
  at OpenSim.Region.Environment.Scenes.Scene.Heartbeat (object,System.EventArgs) <0x0000b>
  at System.Timers.Timer.Callback (object) <0x002a6>
  at (wrapper delegate-invoke) System.MulticastDelegate.invoke_void_object (object) <0xffffffff>
  at (wrapper runtime-invoke) System.Threading.WaitCallback.runtime_invoke_void_object (object,intptr,intptr,intptr) <0xffffffff>

Native stacktrace:

        mono [0x81ab4d7]
        mono [0x818e960]
        [0xb7f04440]
        /lib/i686/cmov/libc.so.6(abort+0x101) [0xb7ce1181]
        ./libode.so(dDebug+0x3c) [0xb42c132c]
        ./libode.so(_Z19dCollideHeightfieldP6dxGeomS0_iP12dContactGeomi+0x943) [0xb42fc213]
        ./libode.so(dCollide+0x149) [0xb42c2189]
        [0x9a4eaeab]
        [0x9a4eaae2]
        [0xa9ff03c]
        ./libode.so [0xb42cb519]
        ./libode.so(_ZN11dxHashSpace8collide2EPvP6dxGeomPFvS0_S2_S2_E+0x95) [0xb42ccb15]
        ./libode.so(dSpaceCollide2+0x12b) [0xb42cd4bb]
        [0x9a4ea877]
        [0xb429f0f1]
        [0xb429e5e8]
        [0xb429dc19]
        [0xb429cc5b]
        [0xb429cabc]
        [0xb65da5f7]
        [0xb65da32c]
        [0xb65da286]
        mono [0x818e75c]
        mono(mono_runtime_invoke+0x29) [0x80b8aa0]
        mono(mono_runtime_invoke_array+0x50b) [0x80ba4be]
        mono [0x80bc65f]
        mono [0x80f5cca]
        mono [0x80f6b28]
        mono [0x80efc24]
        mono [0x8149305]
        mono [0x8162ee8]
        /lib/i686/cmov/libpthread.so.0 [0xb7e2746b]
        /lib/i686/cmov/libc.so.6(clone+0x5e) [0xb7d8872e]

=================================================================
Got a SIGABRT while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries
used by your application.
=================================================================