"Not enough space" error

Have been trying to download EU III - HTTT and keep getting an error as follows once the download has finished and the extraction process begins:

"There was a problem while retrieving your free-space information. You may need to choose a different install or temporary files directory"

 Have tried re-installing the Impulse software, changing installation and Temporary directories, selecting the "Prompt for install directory" option and all of the other solutions which are mentioned in the forum posts I've seen where others have had similar problems.

 Am attempting to download and install to my C: drive which has 261GB (!) free, but the error log says the following

 "Context:    General
Message:    Not enough drive space to install.  Free space:0 Total drive size: 0 Install size: 84141662 Space after install: -84141662
Build #:    1309"

 Any other suggestions? Thanks.