Killing both system.threading.timer object and an early bound dll

[Claire]

This is the first threaded Windows Service application I've written.
I'm using a System.Threading.Timer object to keep looping through a state
engine.
Each state requires the timer to call one or more functions in a 3rd party
DLL making calls to a server across a network.
It's known that the DLL can naughtily hang when it waits for responses from
the network server rather than do a nice timeout. I MUST write the service
so it can recover and keep monitoring.
I want to be able to monitor the timer and, if it's taking too long, I want
to kill it.
Can this be done? (while the timer's stuck in code?)

In addition to this, the DLL is an unmanaged win32 dll that is early bound
and not dynamically loaded (loading dynamically seems a tough job in current
version of dotnet). The Dll is talked to by a wrapper object. If that
wrapper object is Dipose()d of, will the Dll be unloaded along with it or
will it only unload when the application is shut down?
If I really need to load it dynamically, does anyone have a link that shows
an example? All the dll function calls have a single parameter which is a
byte[] and they're declared as cdecl. I've attempted to do similar on a
previous occasion and failed to find any decent examples.

thanks