When I try to upload something to fileize, it shows the loader, and doesn't load at all. I tried uploading a picture once, and I left to go grocery shopping, leaving the computer on, and 1 hour later, it still was showing the loader, not loading at all.

Any Ideas or suggestions?

I have this problem to. You need to make sure you your internet fast. Or you could try again in 2-3 days, there's something wrong with you internet's speed at that time.

Internet Speed
This is what you need, you will need a fast (not really fast, just normal like 100kb above. If you have a really slow net then that means it will take you forever to upload a pic (or a SWF video).

Browser
Switch to another browser if you're using Chrome and try if it works.

File size
If you are uploading a large file then make sure you wait, if it's small then it will upload faster.

Patience
Be patient because sometimes it may take you 5 minutes in uploading files.

I had that problem too...I just refreshed it and reuploaded it then it perfectly worked again :/

If that doesn't still work...Try it again tomorrow or later.

There is a thread up here especifically for fileize issues, and your question was already solved there

Is just a matter of time.