[Zope] Zope leaking memory?

Pound-current (V 1.7+) Zope 2.6.4 Python 2.3.4 RH 7.3 Dual Athalon processors Occasionally, I see Zope gathering very large amounts of real memory. Normally buffering and the like seems to stabalize at around 500MB on a 4GB memory dual processor machine, but occasionally grows to 2.5GB or more. At the same time, CPU usage tends to fully occupy one of the processors for the threads holding all the memory. Clearly there is a problem. Any hints as to where to track down the problem?