Windows Live Mail has stopped working – Multiple messages

I have been using Windows Live Mail successfully but suddenly when composing an email I get a pop-up box saying "Windows Live Mail has stopped working. A program has caused the program to stop working correctly. Windows will close the program and notify you if a solution is available". When I click "Close Program" Live Mail continues working normally for a time but it may appear again whilst entering text and at worst multiple pop-up boxes may flood the task bar. I have tried repairing Live Essentials but this hasn't fixed the problem. The event log shows the event ID is 1001 with Event Name WindowsLiveWriter the problem being a System.Runtime.InteropServices.COMException. I am running Windows 7 (64 bit) SP1.