Giving what you have said, you installation was successful after you hit the "Try Again" button, the problem was rectified and the status became green.
This kind of problems could highly be due to the following three problems:

1) Your Internet browser being Microsoft Internet Explorer version 8, or IE 7 with some security enabled on it.
Solution: Install another web browser as Fire Fox, and always use this browser when you want to connect to Oracle Apps.

2) Sometime, the IP Address you Oracle Enterprise Linux which you synchronize with the Host File IP Address, would have changed due to various reasons, such as your system being in the presence of another Oracle Apps installation, or your Oracle Apps system being just exposed to other wireless network environments.
Solution: Check again the IP Address of the Guest operating system: [Oracle@linux ~]$ /sbin/ifconfig . Note the IP Address down. START > Accessories > Notepad.

Now, right Click Notepad, and Choose “Run as administrator”. (You cannot modify the host file of Windows without this privilege). This will open a blank Notepad file. Click on File menu, and select Open from the drop down menu. Look for the file “hosts” in the directory “C:\Windows\System32\Drivers\etc”. The file “hosts” will be open is a Notepad to be appended. Example: 192.168.0.12 linux.server . Save your note file. Restart you’re your browser.
In the Internet Explorer address bar, type the following: “http://linux.server:8000”

3) Another cause of the problem I have seen is: Not successfully installing the one-off Java Virtual machine (JVM) after click on Security > User > Define with System Administrator responsibility.
Solution: Make sure you initiate the process of installing JVM, and then follow “blindly” the part of the tutorials dealing with this.

You should be fine after the above three investigations!