CPU utilization goes from 10% to 100% gradually over ~60mins of use

I was using spy++ and saw that there was contention happening, but I don't know how much is 'bad'.  How would I determine that such and such code is producing the contention?  Can you offer any advice?

It's never very easy to debug... the way I would approach it is to break the app into smaller pieces.. write out log / trace messages at each thread start / stop  and probably with every other line of code..
In a well synchronized world any amount of thread contention should be avoided (but may not always be feasible).

Are you user a 1 processor system? How is the GC implemented?

I am using a 3.06 intel with HT.  Not sure how to answer GC question... If that gives you any indication ;)

Took a look at the Contention Rate/sec.  It starts at about 1/sec and then after a while the couter increments with larger numbers.  It is at that point that the CPU starts to take off so it seems pretty reasonable to conclude that the two are related.  When you posted earlier you talked about writing trace messages when threads start/stop.  What information would be useful and should be included in the trace messages?  Contention is where multiple threads want to use a global variable correct?  there is only one situation where i use synclock in the app so I assume that has to be the source of the problem.  I tried to implement it using the smallest "footprint" possible.  Can you offer some advice on how to structure the synclocks?  Or possibly an alternative?  I am using Synclock to batch some SQL together and have included a code snipet below.  Thanks!

        SyncLock BatchSQL
            BatchSQL.Append(strSQL)
            BatchSQL.Append(";")
            BatchSQLCount += 1

            If BatchSQLCount >= 250 Then
                'If the SQL batch is big enough then copy the batch to a temp string variable and clear the global string variable
                SQLTemp = BatchSQL.ToString

                BatchSQL.Remove(0, BatchSQL.Length)
                BatchSQLCount = 0

                ExecuteBatch = True
            End If
        End SyncLock

that is not a long held lock and should not cause too much of an issue.

(form previous questions) there are other variables used within your app that are shared the async io on the socket is a good example.

I took a look at the .net memory profiler.  I am new to the multithreading scene so it is taking me a while to understand what I am looking at.  What I think I have discovered is that a class I am creating to pass data to a thread is not being freed after the thread is finished.  So the question I think that I want to ask is how do I make sure that I have properly "disposed" of a class that has been used to send data to a thread after the thread has completed its job?