Earlier today I encountered an issue where I could not install new modules into my Drupal 7 instance. The error message is:

Warning: fileowner() [function.fileowner]: stat failed for temporary://upd92FE.tmp in update_manager_local_transfers_allowed() (line 924 of C:\inetpub\wwwroot\drupal\modules\update\update.manager.inc).

After some nosing arround in the code. I found the solution. Posted it at http://stackoverflow.com/questions/4632779/drupal-7-is-unable-to-install-modules/4633270#

Hope this helps.

– benjamin wong