title: UITableView crash gives 'CALayerInvalidGeometry', reason: 'CALayer position contains NaN: [160 nan]'
body: <p>I have a custom table view in my app. I have implemented the "Load More" feature to the table which loads 25 rows at a time. The problem is after loading 2 times the app crashes giving 'CALayerInvalidGeometry', reason: 'CALayer position contains NaN: [160 nan]' as error on OS 4.2 and above. </p>
  
  <p>On OS below 4.2 one of the cell goes missing and there is blank space between in the middle of the table. It do not give any crash. But it still gives the error mentioned above.</p>
  
  <p>I check to see where can the division by 0 can occur in my code but i couldnt find any. Following the stack trace i fond. So i cannot even check where this exception is happening. </p>
  
  <p>Anybody have any idea ??</p>
  
  <pre><code>    0   CoreFoundation                      0x020ccbe9 __exceptionPreprocess + 185
   1   libobjc.A.dylib                     0x022215c2 objc_exception_throw + 47
   2   CoreFoundation                      0x02085628 +[NSException raise:format:arguments:] + 136
   3   CoreFoundation                      0x0208559a +[NSException raise:format:] + 58
   4   QuartzCore                          0x0182396a _ZL18CALayerSetPositionP7CALayerRKN2CA4Vec2IdEEb + 177
   5   QuartzCore                          0x018238b5 -[CALayer setPosition:] + 42
   6   QuartzCore                          0x018237cc -[CALayer setFrame:] + 763
   7   UIKit                               0x0073c307 -[UIView(Geometry) setFrame:] + 255
   8   UIKit                               0x008c718a -[UITableViewCell setFrame:] + 166
   9   UIKit                               0x0077aa08 -[UITableView(UITableViewInternal) _createPreparedCellForGlobalRow:withIndexPath:] + 1160
   10  UIKit                               0x0077077f -[UITableView(UITableViewInternal) _createPreparedCellForGlobalRow:] + 75
   11  UIKit                               0x00785450 -[UITableView(_UITableViewPrivate) _updateVisibleCellsNow:] + 1561
   12  UIKit                               0x0077d538 -[UITableView layoutSubviews] + 242
   13  QuartzCore                          0x01828451 -[CALayer layoutSublayers] + 181
   14  QuartzCore                          0x0182817c CALayerLayoutIfNeeded + 220
   15  QuartzCore                          0x0182137c _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 310
   16  QuartzCore                          0x018210d0 _ZN2CA11Transaction6commitEv + 292
   17  QuartzCore                          0x018517d5 _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 99
   18  CoreFoundation                      0x020adfbb __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 27
   19  CoreFoundation                      0x020430e7 __CFRunLoopDoObservers + 295
   20  CoreFoundation                      0x0200bbd7 __CFRunLoopRun + 1575
   21  CoreFoundation                      0x0200b240 CFRunLoopRunSpecific + 208
   22  CoreFoundation                      0x0200b161 CFRunLoopRunInMode + 97
   23  GraphicsServices                    0x02611268 GSEventRunModal + 217
   24  GraphicsServices                    0x0261132d GSEventRun + 115
   25  UIKit                               0x0071542e UIApplicationMain + 1160
  </code></pre>