I have been dealing with this issue for some time now. For the last month I have had to pull the power every 7 days like clockwork. I poked around in cron and found about 30+ start/stop entries for clamav. I believe clamav (anti-virus essentials) may have caused the freezing in my case. It takes around 40%+ for one scan and the scans take place every Saturday which is when I have to pull the power. Here is a link in relation to high cpu High CPU on EX4 seems to be caused by ClamAV
I have a power schedule on my box so every time it boots another clamav start/stop entry is added. I have disabled the anti-virus schedule and will check in 7 days to see if the problem has gone away.
Update: 7 days on and my ex4100 appears to be operating normally. Time will tell if this has resolved the issue but so far so good.
