Uploading A File

I'm trying to upload, to my profile, a screenshot of my current team and the upload has now failed twice, the message I get says:

"Nottingham Forest (Nottm Forest_Players)-4.png : The upload failed, this file is too big maybe, or the extension is not allowed?"

In my personal file space the title size is a lot smaller than the maximum file size so it's not a problem of it being too big, so what does it mean that it's not allowed and how can I fix this?

I'd just use a 3rd party site to host your image(s) instead, like imageshack. Then when you want to add screenshots you can just use the {img}imagelink{/img} tag in your posts.

Thanks, will do