Can't upload any media files

Hi Everyone,
I have been unable to upload any Media. I have tried both mp3’s and picture flies, of all sizes, but I just keep getting this message.

mp3” has failed to upload due to an error
The uploaded file could not be moved to /var/www/vhosts/mydomain.com/httpdocs/wp-content/uploads.

This happens just after the crunching stage.

I have tried the following.

changed all file permissions to 777
tried different browsers
reinstalled wordpress several times and created a new database each time
Uploaded an mp3 file with Filezilla to the uploads folder. I can see it in the file, but WordPress can’t.
I have used both flash upload and the browse method.
created a .htaccess file

Nothing works and there is no definitive answer in the forums. Please can anyone help. I have wasted hours and hours messing around with the problem. It’s driving me mad! Many thanks.