Error after video uploads

Hi, I have free dolphin running on 2 domains, I can't upload video to either of them. After the file reaches 100% I get an approved screen for a second, then an alert  upload file error. The videos never appear anywhere.

I've checked that file save and auto approve are on in Ray.

I've tried different formats .flv .wmv with the same results.

mp3 files upload with no problems.

Can anyone help?

Thanks,