I have exactly the same problem and I do not get rid of it.
The error happens, while clicking on the button
selenium = myDevice.getSelenium();
selenium.selectWindow("");
Thread.sleep(2000);
selenium.click("btnMyButton");
This is the html code of the button:
<input name="btnMyButton" id="btnMyButton" type="button" onclick="javascript:MyFunction();" tabindex="0" disabled="disabled" value="btnMyButton" title="btnMyButton" />
Remark: The button is disabled by default, but enabled by java script. And yes I ensured that it is enabled during my test.
The js function looks like this:
function MyFunction()
{
if (document.all.txtLogin.value.length > 0)
{
document.all.txtPassword.value = "";
var result = showModalDialog("MyPage.aspx),null,"scroll:no;status:no;unadorned:no;help:no;edge:raised;center:yes;resizable:no;dialogHeight:160px;dialogWidth:360px");
}
}