problem handling multiple windows in webdriver

Scenario:

1. Step-1.Click link from window-1.New window gets opened.Say it as window-2.
2. Step-2.Do action on window-2.
3. Step-3.Close window-2.
4. Step-4.Move focus to window-1
5. Step-5.Click an element in window-1(Here a New window is getting opened)
6. Step-6.Click link from window-1 again opens another window-say it as WINDOW-2
7. Step-7.Do actions on WINDOW-2
8. Step-8.Close window-2
9. Step-9.Move focus to window-1 again and perform action.
10. Step-10.Close window-1.

---Clicking the element on parent window on step-5 opens in a new window---**

String oldTab = driver.getWindowHandle();
//clicking link to open new window
if(driver.findElement(By.xpath("element")).isDisplayed())
{ 
   Actions aBuilder = new Actions(driver);                                                            aBuilder.keyDown(Keys.SHIFT).click(link).perform();
   ArrayList<String> newTab = new ArrayList<String>(driver.getWindowHandles());
   newTab.remove(oldTab);
   driver.switchTo().window(newTab.get(0));
   //peform action
   driver.close();
   driver.switchTo().window(oldTab);
}
String oldTab1 = driver.getWindowHandle();
driver.navigate().refresh();
//Clicking link to open in new Window
if(driver.findElement(By.xpath("element")).isDisplayed())
{ 
   Actions aBuilder1 = new Actions(driver);
   aBuilder1.keyDown(Keys.SHIFT).click(link1).perform();
   ArrayList<String> newTab1 = new ArrayList<String>(driver.getWindowHandles());
   newTab1.remove(oldTab1);
   driver.switchTo().window(newTab1.get(0));
   //perform action
   driver.close();
   driver.switchTo().window(oldTab1);
}