Which version and branch of huggle are you using? 0.9.6

Please provide any additional information below.KeyNotFoundException: The given key was not present in the dictionary. at System.ThrowHelper.ThrowKeyNotFoundException() at System.Collections.Generic.Dictionary2.get_Item(TKey key) at Huggle.Requests.RollbackRequest.Done() at Huggle.Requests.Request.ThreadDone() at Huggle.Misc.CallbackInvoke(Object TargetObject) KeyNotFoundException: The given key was not present in the dictionary. at System.ThrowHelper.ThrowKeyNotFoundException() at System.Collections.Generic.Dictionary2.get_Item(TKey key) at Huggle.QueueForm.get_CurrentQueue() at Huggle.QueueForm.QueueForm_FormClosing(Object s, FormClosingEventArgs e) at System.Windows.Forms.Form.OnFormClosing(FormClosingEventArgs e) at System.Windows.Forms.Form.RaiseFormClosingOnAppExit() at System.Windows.Forms.Application.ExitInternal() at System.Windows.Forms.Application.Exit(CancelEventArgs e) at System.Windows.Forms.Application.Exit() at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnUnh andledException(UnhandledExceptionEventArgs e) at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnUnh andledExceptionEventAdaptor(Object sender, ThreadExceptionEventArgs e) at System.Windows.Forms.Application.ThreadContext.OnThreadException(Exception t) at System.Windows.Forms.Control.InvokeMarshaledCallbacks() at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) EventType : clr20r3 P1 : huggle 0.9.6.exe P2 : 0.9.6.0 P3 : 4bf3c224 P4 : huggle P5 : 0.9.6.0 P6 : 4bf3c224 P7 : d81 P8 : 1b0
P9 : system.nullreferenceexception
OS: Windows NT 5.1 SP3 (XP SP3 BUILD 2600.xpsp_sp3_gdr.100216-1514) 1024 MB system memory

Not sure what exactly caused huggle to crash, however, i've noticed if windows generates a report and states huggle must close, if you dont acknowledge the dialog and say.... drag it off the screen, huggle will keep running. I'm almost positive i was just rollback'n like usual. I'm pretty sure it happened after a rollback/warn request. I've also noticed crashes when you click the [x] cancel button to cancel a current request.

To supplement crash conditions mentioned in the first comment - I've had crashes happen primarily when using a few different buttons that aren't the big danger triangle for rollback/warn actions, or the arrow keys for browsing back and forth through diffs I've already looked at. The curving-up-an-left arrow for non-warning reverts will often cause a crash, as will the back/forward buttons for browsing all diffs (not just ones I've previously browsed). Sorry I'm not being more precise or thorough but I can't test for this comment because a) I'm a fairly new Huggle user & don't have the interface memorized yet, and b) I have another issue that's preventing me from running it at present (Invalid URI warning, detailed on w:Huggle/Feedback.).

update