Selenium logs out automatically - selenium

Question

I am working on VCM and have created some test script using Selenium and TestNG (not using webdriver).
The problem is that as soon as it logins it automatically logs-out showing the error that the link was not found. If individual run the scripts run perfectly but when running the Suite it always fails showing above mentioned error.
Here's my code for reference:
#BeforeTest
public void setup()
{
selenium = new DefaultSelenium("localhost",4444,"*firefox","http://BaseURL/");
selenium.start();
selenium.windowMaximize();
}
#AfterTest
public void teardown()
{
this.selenium.close();
}
#Test public void testTC_07() throws Exception {
selenium.open("http://BaseWebsite");
selenium.type("name=j_username", "UserId");
selenium.type("name=j_password", "PassWord");
selenium.click("id=login-button");
selenium.waitForPageToLoad("60000");
selenium.click("id=href_Menus");
selenium.waitForPageToLoad("60000");
selenium.click("link=TestContents");
selenium.waitForPageToLoad("60000");
selenium.click("link=Test");
selenium.waitForPageToLoad("60000");
selenium.click("link=Test_title");
selenium.waitForPopUp("Pop Up Window", "60000");
selenium.selectWindow("null");
verifyEquals(selenium.getTitle(), "Test_Title Properties Window");
verifyTrue(selenium.isTextPresent("Title"));
selenium.type("id=textbox", "");
Thread.sleep(10000);
selenium.click("id=doOK");
String title= selenium.getTitle();
if(title!="Window Title"){
selenium.close();
selenium.selectWindow("null");
selenium.click("link=Logout");
selenium.waitForPageToLoad("60000");
}
else{
TC_07.fail(null);
this.selenium.close();
}
}