when did you get that exception, right after server start? do you get the same exception with the original parameters?
Remove the NewRatio - first because a ratio of 1 is about the worst thing you can do - it almost guarantees that all GCs will be full GCs. Second, JDK 6 is much more adept at adjusting the young gen size to fit your actual usage (earlier versions of the JVM were really bad at that) - for JDK 6 I recommend letting the JVM determine the young gen size.
If that does not solve the problem, then set -XX:+PrintHeapAtGC and post the console output (you will want to redirect to a file).
This exception occurs after sometime, not imediate restart of the server. In our application after one/two days.
With original parameters alos we use to get the same exception, however frequency of occurance was once in a 15 days or Month.