postback javascript error

Whenever my form postback from a dropdown control I get a javascript error stating, "Object doesn't support this property or method." I think this happens on theform.submit(); line below. Does anyone know how I can fix this problem?

function __doPostBack(eventTarget, eventArgument) {
var theform = document.Form1;
theform.__EVENTTARGET.value = eventTarget;
theform.__EVENTARGUMENT.value = eventArgument;
theform.submit();
}

Thanks,

James

I found my problem. I have a button control with the id="submit". For some reason the postback doesn't like buttons with the id="submit." If anyone know why please let me know.

James