Our WordPress 2.8.6 installation is coming back multiple different errors when attempting to edit theme files via wordpress-admin. The errors are the following:

"Invalid index."

"The information area passed to some system call is simply too small"

"The parameter is incorrect."

We have attempted deactivating all plug ins with no success. We attempted developing a blank "plug ins" directory as well as still experienced these errors. Some theme files we could edit (very couple of), but many give among the three errors above. We attempted switching to the WordPress Default theme with similar results.

This installation is running on the Home windows 2003 Server, IIS 6, PHP 5.3., FastCGI, and MySQL 5.1.40-community.

Sounds like your IIS config is messed up.

Try posting on serverfault.com too, this really is much more of a server config problem than the usual programming problem I believe.