Included Password plugin does not work with hmail and php 5.5.7 on Windows

[RickSaysMeh]

Disclaimer: I have never successfully configured the password plugin to work with hmail on Roundcube.

My system:
Windows 2008 R2 Standard
hMailServer 5.4-B1950
Roundcube 0.9.5
PHP 5.5.7 non thread safe

I have enabled dcom in php.ini. I have added the IUSR account to the DCOM properties of hMailServer. I have modified the password config.inc.php to use hmail, remote server=false, server=localhost. In Roundcube web interface I see the password option in Settings, but when I enter a new password it just shows the standard "The website cannot display the page" message with the URL: http://serveraddress/?_task=settings&_action=plugin.password-save

Previously with PHP 5.3 and Roundcube 0.9.2. It would display an error message on the password page (can't remember what it said).

Any ideas?

EDIT: RESOLVED
With PHP 5.5.7 in the php.ini file you need to both:
Uncomment the line: com.allow_dcom = true
Add the line: extension=php_com_dotnet.dll

In the DCOM Config properties for hMailServer, add IIS_IUSRS to Launch and Activation Permissions with local allow access (I also added it to Access Permissions and Configuration Permissions, but I don't think those are necessary)

After making these changes, the password plugin works as expected!

[SKaero]

Is there anything in the server logs?

[RickSaysMeh]

There is nothing in the Windows logs.

The Rouncube log shows this entry:

[01-Jan-2014 20:38:02 US/Eastern] PHP Fatal error:  Class 'COM' not found in C:\inetpub\wwwroot\roundcube\plugins\password\drivers\hmail.php on line 26

[RickSaysMeh]

Sorry for the double post.

I added this line to the php.ini file:
extension=php_com_dotnet.dll

Now I don't get the page cannot be displayed error, but roundcube pops up an error saying the password could not be saved. This is what is in the log file:
[01-Jan-2014 21:14:58 -0500]: Plugin password (hmail driver): Failed to create COM object `hMailServer.Application': Access is denied.
[01-Jan-2014 21:14:58 -0500]: Plugin password (hmail driver): This problem is often caused by DCOM permissions not being set.

I gave the IUSR account access in DCOM, but maybe that wasn't right?

[SKaero]

I'm not a Windows expert so I'm afraid I can't be of too much more help, but it sounds like this problem: http://www.roundcubeforum.net/index.php?topic=7329.0

[RickSaysMeh]

I managed to resolve the issue! See my edit on the first post.

Also, can a moderator move this to the Resolved section?