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In the tradition of the army and Microsoft, you will find many items abbreviated for easy of use.

DLL: Dynamic-Link Library.

DUN: Dial-Up Networking.

56k Modem Myth Modem Connection Dial-Up Errors INIT String Line Noise

Error 745: Reinstall DUN

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When you attempt to connect to a remote computer using DUN, you may receive the following error message: 

Error 745: An essential file is missing. Re-install Dial-Up Networking

This error message can occur when a Dial-Up Networking dynamic-link library (.dll) file is missing or damaged.

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys and Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT or Windows 2000, you should also update your Emergency Repair Disk (ERD).

To resolve this issue, remove and reinstall Dial-Up Networking:

  1. Click Start, point to Settings, and then click Control Panel.

    Double-click Add/Remove Programs.
  2. Click the Windows Setup tab, click Communications, and then click Details.
  3. Click the Dial-Up Networking check box to clear it, click OK, and then click OK again.
  4. Click Start, click Shut Down, click Restart Your Computer, and then click Yes.
  5. Click Start, point to Programs, and then click Windows Explorer.
  6. If it exists, rename the Rasapi32.dll file located in the Windows\System folder. For information about how to rename a file, click Start, click Help, click the Index tab, type renaming, and then double-click the Renaming files topic.
  7. Use Registry Editor to check the path value under the following registry key:
    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\RemoteAccess
    \Authentication\SMM_Files\PPP
  8. NOTE: The above registry key is one path; it has been wrapped for readability.

    If the path reads Rasapi32.dll or SMMscrpt.DLL, perform steps 9-15. If the path reads other than Rasapi32.dll or SMMscrpt.DLL, edit the path to read Rasapi32.dll, extract a new copy of the Rasapi32.dll file, reinstall Dial-Up Networking, and skip the remaining steps.

    Extract a new copy of the Rasapi32.dll file from your original Windows 95/98 CD-ROM or floppy disks into the Windows\System folder. To do this, use the appropriate method:

Modem Properties Not Available in Modem Tools

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When you modify your modem's properties, you may experience one of the following symptoms: (Win 95/98)

1. The Configure button is unavailable in HyperTerminal or Dial-Up Networking.

2. When you click your modem and then click Properties in the Modems tool in Control Panel, you receive the following error message:

(removing and reinstalling the modem will not fix this problem).

This error is usually caused when the Modemui.dll file is damaged. 
To fix this problem:

1.  Use Windows Explorer or My Computer to rename the Modemui.dll file in the Windows\System folder to Modemui.xxx.

2.  Extract a new copy of the Modemui.dll file to your Windows\System folder.

This page was last updated on Sunday, December 03, 2000 .

If you have any comments, suggestions or questions Email: [email protected] or [email protected].