I think you have a IRQ conflict. It sounds like your modem is using a IRQ that is already in use. Read the manual and see if you can change your IRQ settings for the cards you have.

Worse case, get a external modem.

: My husband built a computer for me,I tried to install a modem. Computer kept freezing up,had to restartby turning off( woldn't do ctrl+alt+del) Last time it did when it checked the system for errors it found some but wouldn't allow to copy files to A: to save. Then froze again and would not come back up since. Cannot access any drive except A:. Will not allow to reboot MS DOS either.Please help !