IBM ThinkPad Modem Does Not Work After You Upgrade from Windows NT 4.0 to Windows XP Professional

After you upgrade your IBM ThinkPad computer from Microsoft Windows NT 4.0 Workstation to Windows XP, the modem may not work, even though the modem appears to be working properly in Device Manager.

To work around this problem:

1. Search for the Mwwdmhlp.dll file. To search for a file, click Start, click Search, and then follow the instructions on the screen.
2. Rename the Mwwdmhlp.dll file to Mwwdmhlp.old. To rename a file, right-click it, click Rename, type the new name, and then press ENTER.
3. Restart your computer so that Windows System File Protection can replace the original Windows NT 4.0 file with a copy from the system catalog.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.