New Java Applet Window won't come to top

Hello everyone, I have an applet that shows different options to the client, each option opens another applet window that shows information and data related to the selected option, in this second applet window I have different buttons for creating new data, deleting and editing, etc. each time an edit or delete button is pressed without a set of data being selected there's a message 'you need to select a row'...

So far so good, the problem is that when the user selects the create option or actually select data and chooses delete or edit, the new applet window shows up, but doesn't come to the top, it just remain in the background and the window with the create, delete and edit options, keeps active, every time i try to select the new window it just flashes and makes an error sound but the previous window still keeps active...

The application was working ok before, I'm actually not sure when was the last time the application was used and didn't show any problems, so I don't know if this could be due to some incompatibility in the Java versions since the applet code is kinda old, the versions are as follows:

Server Side:
java version "1.5.0_20"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_20-b02)
Java HotSpot(TM) Client VM (build 1.5.0_20-b02, mixed mode)

Client Side:
java version "1.6.0"
Java(TM) SE Runtime Environment (build pwi3260sr8fp1ifix-20100903_02(SR8 FP1+IZ83654))

Since there haven't been any code change since almost two years, I'm inclined to believe the problem resides in the version or any update maybe from java or the explorers (IE and FireFox both show the same problem)

Any other ideas? or suggestions as to what could be wrong? or how should I attack the problem?