WordPress and Plugins: Download failed.: Failed to write request

Hi,

I have been getting the following error when I try to update plugins or reinstall wordpress through the dashboard:

Download failed.: Failed to write request to temporary file.

I have been looking at all the forums and have done nearly everything suggested to me. I have spoken to the host and following their instructions set up a php.ini file to direct to a new temporary directory which is empty, I have also spoken to them about space and the SSH quota but they have told me there are no errors to report and there is plenty of space.

The host is being really helpful and have spent a lot of time on it, so I don’t think they are trying to be unhelpful.

Has anyone got any ideas what else I could try, and if nothing works, would restoring a backup to when these updates were working be the way to go?

Thanks so much!