java.exe maxing out my memory and CPU usage oscillates between 2-80%

Symptom: Users start reporting slow system performance and soon after we have total system freeze.  What I have found is on my Application server there is a "java.exe" process that is using an increasing amount of system memory as well as causing my cpu usage to scillate between about 2-80%.  I have been monitoring and restarting the server on the weekends to prevent crashes during the week.   Seems to happen every two weeks or so and the only solution so far is to restart the servers.