Error in Scrolling Intellisense

I am receiving the following error when scrolling in items in an Intellilist.

I probably have something define wrong but can you let me know where to look for this error:


Top Level Exception
Type: System.ApplicationException
Message: The MarkupLabel text was not in XML format:

The ':' character, hexadecimal value 0x3A, cannot be included in a name.
Line 1, position 13.
Source: ActiproSoftware.WinUICore
Stack Trace: at ActiproSoftware.MarkupLabel.MarkupLabel._1()
at ActiproSoftware.MarkupLabel.MarkupLabel.set_Text(String value)
at _10._1(String )
at _9._7()
at _9._1(Object , EventArgs )
at System.Windows.Forms.Timer.OnTick(EventArgs e)
at System.Windows.Forms.Timer.Callback(IntPtr hWnd, Int32 msg, IntPtr
idEvent, IntPtr dwTime)

Thanks