Frequently, our computers come across an unknown file extension. It need to open, but computer seems to have no program required to open it.
Sometimes, you could search the file extension on the Internet, which someone else may come across such a problem on. Most of bloggers like to post solutions about opening an unknown extensioned file.
So file extension unknown is not a problem. If you find nothing helpful, you can post this problem online at technical support forums. you may get a support quite quickly.
If you find a solution to open a file, which is named with a file extension unknown, you may post it on your own webpages, which can give other people an offer to support.
(brought to you by your friend at www.ifileextensionunknown.com)