If you are running WordPress on IIS7 and are having trouble updating your plugins and/or WordPress itself, you might have an impersonation setting problem. Check your PHP error log (sometimes in C:\temp). If you see and error message like:
“PHP Warning: touch(): Unable to create file /tmp/wordpress-3.tmp because No such file or directory in…”
it probably means you have fastcgi.impersonate set to 1 in your php.ini and the anonymous user, IUSR, doesn’t have the rights to modify files in your site directory.
To fix this, right-click on the website directory and select Properties. On the Security tab, add the IUSR with Modify permissions. Be sure to click Advanced after and choose to replace permissions on the sub-folders.