Error publishing Tridion 2009 template

We just started getting some errors when trying to publish pages (.NET) - in Tridion 2009. It started with the intermittent, classic "RenderComponentPresentation exceeded the maximum number of failure errors 0", and then progressed to a complete failure.

We can view the pages correctly, so I cannot believe that this is due to the actual code template.

Unfortunately, I do not control the field that it runs on, so I can’t run any debugging code, etc ... so this is a shot in the dark!

Stack trace below:

Event Type:        Error 
Event Source:        Publishing 
Event Category:        None 
Event ID:        100 
Date:                22/05/2012 
Time:                14:28:22 
User:                N/A 
Computer:        XXXXXXXXXX
Description: 
Exception has been thrown by the target of an invocation. 
Old format or invalid type library. (Exception from HRESULT: 0x80028019 (TYPE_E_UNSUPFORMAT)) 


Component: Tridion.ContentManager.Publishing 
Errorcode: 0 
User: NT AUTHORITY\SYSTEM 

StackTrace Information Details: 
   at System.RuntimeMethodHandle._InvokeConstructor(Object[] args, SignatureStruct& signature, IntPtr declaringType) 
   at System.RuntimeMethodHandle.InvokeConstructor(Object[] args, SignatureStruct signature, RuntimeTypeHandle declaringType) 
   at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) 
   at System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) 
   at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) 
   at Tridion.ContentManager.Session.GetObject(String uri) 
   at Tridion.ContentManager.Publishing.Publisher.QueueMessageHandler.HandleMessage()