I don't really know for sure what's going on. But it is an operating system problem, to do with file associations to applications, not a FileMaker problem per se. All your icons still look like FileMaker 10 except Home, which looks like FileMaker 11.
You don't say what OS you're running, Tiger, Leopard, Snow Leopard? There have been big changes to this part of the OS. Apple has transitioned away from the simpler (but reliable) method of creator codes to a more flexible modern system. There have been some rough spots.
If you right-click on the file, there is an "Open with" command. If you hold the Option key it changes to "Always open with". Do that, and choose FileMaker 11. A similar "Open with:" command appears if you "Get Info" (cmd-I) for a file. It has an additional button to "Change All...", which will associate all FileMaker "fp7" files on the machine with FileMaker 11.
Just how well this works depends on your OS. It works well in later versions of Snow Leopard. I don't know all technical details, but the above should work.
I did what was mentioned above and the same thing happened on the re-start. The operating system is 10.6.4
If you rename the file something other than Home, does the same thing happen?
If you duplicate the unopened file with Finder, does the same thing happen?
If you open the file and SAVE AS Clone, does the same thing happen?
If you download, install, and run AppleJack, does the same thing happen?
Onyx also has a Rebuilding: [x] LaunchServices option, on its Automation tab (uncheck any you don't want to run).