Ukoliko se radi o eksternom, seriskom modemu, njemu drajveri ne trebaju. To sto se kod njih naziva drajverom je nesto drugo, moze i bez toga. Izuzev ako nemas ono "sekretarica" i slicno. Druga je stvar sto ga XP vise ni ne primecuje. Ubedjen sam da ne bi primetio ni neki drugi modem. Da sam na tvom mestu, ja bih na Google trazio "problem sa com portom nakon SP2" mozda se nesto nadje.
http://forums.thetechguys.com/archive/index.php/t-8610.html ovde ima nesto sicno, mada ne i identicno, pokusaj, ne kosta nista:
try this (if you haven't already): (1) Disconnect the modem completely; (2) Go to desktop and right click on My Computer and select Properties; (3) Click on Hardware tab, click on Device Manager; (4) Find the modem tree, open it, right click the installed modem and select Uninstall; (5) When the Confirm Device Removal box pops up, select OK. (6) Exit out, then SHUT DOWN (NOT restart) your machine. Once the computer is off, reboot to ensure the system does not still "see" a modem". Shut down again, then reconnect, switch on the modem then power the computer back up. XP should now detect the modem and install its own drivers as it boots. P.S. - As much as I dislike saying this, I would let XP install its native driver rather than the OEM driver (unless it is "signed" - i.e., WHQL approved). I have a US Robotics 56K and XP simply would not "play nice" with the USR drivers.