pppoe dropping connections

Hi,
My main router keeps dropping pppoe connections. I have looked through all the logs and can see no reason for this.
Its dropping between 20-80% of the connections and they can be wireless or wired connections.
Router:
RB493AH
v4.5
50 Users.
CPU Load Average 50%

Could excessive load cause it to drop connections? I have seen the CPU load spike past 90%.

Any Ideas welcome!

Thanks

The pppoe message i have receiving is:
:terminating… - peer not responding

Could I simply increase the timeout for disconnections to see if I can prevent this?
If so Where would I configure this?

check the keep-alive-timeout setting on pppoe

M.