RNAAPP causing error

Although I do not use my dialup modem, I have been getting "illegal procedure errors occasionally in the last week or so in RNAAPP.  I have also had a communication problem with a serial port communication with an old HP handheld.  I don't know if the problems are related.  The hardware profile indicates no malfunction of the modem.  I can send a fax without a problem so I know that the modem works properly.  A suggestion of a cure from Google is to overwrite the rnaapp.exe file.  (In DOS, extract /a d:\win98\win98_cab rnaapp.exe. Prompt, overwrite?, yes.)  I have not done this.  My system is a Dell XPS t with Win 98SE.  I would appreciate suggestions.