If you are running ISS8 (web server) then the file path is different then the default for Unix. Make sure you have the temporary folder setup correctly on your settings in Drupal and the folder has write permissions.
You can follow this article at step 5 and 6. Create the folder:
Drupal uses the Sites\Default\Files directory to store temporary files and therefore must be able to write and modify files in this folder.
- Create the folder:
C:\inetpub\wwwroot\Drupal>md sites\default\files