DCOM. I'm sure it sounded like a good idea at the time, but in the real world it generates a lot of headaches. Here's some common DCOM, COM+ and WMI errors along with some fixes. There's also some scripts and registry keys at the end of article to help automate the fixes.

CoCreateInstance Errors

Error: CoCreateInstance for APPLICATION.NAME returned 80070005

Cause: This is an access denied error. Usually this is a result of not being to launch the application on the remote server.

Resolution: You'll need to open Component Services on the remote server/workstation and modify the Access, Launch, and Configuration permissions for the particular application. If you're getting this locally, do the same.

Windows Errors

Error: You do not have access rights to Logical Disk Manager on computer

Cause: This error is the result of incorrect DCOM permissions and/or Windows Firewall settings.

Resolution: Option A If you're connecting to a remote computer, make sure you have port 135 set as an exception on both firewalls. You may also need to add dmremote.exe to the exceptions list.

1. Start-->Run, type firewall.cpl and press OK
2. Click on the Exceptions and add C:WINDOWS\system32\dmremote.exe and port 135

If that doesn't resolve it, you'll need to add some additional permissions.

1. Start-->Run, type dcomcnfg and press OK
2. Expand Component Services and then click on Computers
3. Right click on My Computer and click on Properties
4. Click on the COM Security tab
5. Under Access Permissions click on Edit Limits
6. Grant ANONYMOUS LOGON the Remote Access permission
7. Under Launch and Activation Permissions, click Edit Limits
8. Grant Everyone Remote Activation and Remote Launch permissions
9. Click OK twice and reboot the computer

Option B If its you're local PC, you'll need to correct the DCOM permissions.

1. Start-->Run, type dcomcnfg and press OK
2. Expand Component Services and then click on Computers
3. Right click on My Computer and click on Properties
4. Click on the Default Properties tab
5. Set the Default Authentication Level to Connect
6. Set the Default Impersonation Level to Identify
7. Click OK and reboot

Error: Unable to open Component Services (dcomcnfg). The MMC closes instantly as you expand Computers. This also resolves the Win32: Access Denied WMI error (see Option B above).

Cause: This is a combination of bad DCOM permissions and a messed up COM+ system. Usually this is accompanied by several COM+ errors in the event log.

Resolution: Reinstall COM+ and reset the DCOM permissions. Its a simple process.

1. Open a command prompt
2. Type ren %WinDir%\System32\Clbcatq.dll %WinDir%\System32\~Clbcatq.dll
3. Reboot the computer
4. Open regedit
5. Delete the following key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\COM3
6. Open a command prompt
7. Type cd %windir%
8. Type rmdir /s Registration
9. Open Control Panel
10. Open Add/Remove Programs and then click on Add/Remove Windows Components
11. Simply click next to start the reinstall. You may need your Windows CD. If you have IIS installed, run the following command: rundll32 %windir%\system32\inetsrvwamreg.dll, CreateIISPackage
12. Reboot the computer

Useful Registry Keys

Reset DCOM Permissions - [HKEY_LOCAL_MACHINESOFTWAREMicrosoftOle]
"EnableDCOM"="Y" "LegacyAuthenticationLevel"=dword:00000002
"LegacyImpersonationLevel"=dword:00000002

Reference Articles

• How to clean up a damaged COM+ catalog - http://support.microsoft.com/kb/315296
• You cannot use the Computer Management feature on a Windows XP SP2-based computer to access Logical Disk Manager on a Windows Server 2003-based computer - http://support.microsoft.com/kb/902430

If you get the error The COM+ event classes could not be registered then do the following:

1. REGSVR32 ole32.dll
2. After that, reinstall the COM+ event classes with the control panel.

There is a wiki article with mor info if required.