Based on what your describing, it sounds like a loop is not detected in your network and spanning tree is not running. The reason i say this, if there is a broadcast storm it will deplete your bandwidth over a period of a day or a couple of days making everything go to a crawl. When you say you reboot the switches and everything works, it is clearing out the mac tables and starting over. I would look into your network for any duplicate cables setup between switches and verify that spanning tree is enabled. If that is the case, i would look for possibly a squeeling nic or something on the network that is wrecking havoc. Hope this helps, just my thoughts.
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Remote Network Monitoring (RMON) was developed by the Internet Engineering Task Force (IETF) to support...