My WinXP desktop has an integrated "Motorola SM56 Speakerphone Modem" (software modem), which I can't successfully install. After downloading and installing driver from motorola site, "Device Manager" shows yellow "!" with "device cannot start".
Before that I tried installing from the WinXP Disc, and also from Windows Update, plus some other less reputable sources... with no success.
A hardware problem is unlikely since this modem recently worked on this coimputer with the same OS (before I formatted the entire hard-disk and reinstalled the OS).