Cannot open (com) port

I've had to to do a complete reinstallation of a Gateway computer after a "friend" re-set the hdd to a non-dos partition. All has gone well, except for the modem. It responds to diagnostics, but won't connect. (No dial tone)
The phone line tests OK. Had this problem before - failed dial-out circuit. OK, so install a new modem (internal).
System recognises it on bootup & drivers installed OK.
Device manager sees com ports 1 & 2. & modem auto installed on com 3. Cannot query modem using diagnostics;- "unable to open port." Same result when trying to dial out.
Is something loaded at startup taking control of the port, or is the problem related to interrupt or address settings? Also, is there a way to find out what has the port open other than trial & error (eg something like 'netstat', but which flashes by so quickly that it's not useful). BTW, I have uninstalled & re-installed several times. And re-booted after changes. Also, ctrl+alt+del shows more apps than appear in msconfig .startup list'.
I would be most grateful for pointers as to what the various com port settings should be, and tips on finding out what (if anything might have the port open.

 

If you don't have anything installed on COM1 or COM2, remove them in Device Manager and restart. On bootup, go into the setup program and disable COM1 and COM2. Save settings and exit. Boot to Windows and see if your modem will reinstall. If not, remove it in Device Manager and reboot. Windows should find it and reinstall it. When it attempts to install a Windows driver click cancel and run the installation program that came with the modem. I think that should do it. Clydeo22.

 

Thanks for a prompt reply & suggestion. I'll try this asap (probably late this week. And let you know the results.
I suspect that the setup disk doesn't have a setup program. Just .inf files. In this case would a right click on the inf followed by install suffice?
Thanks again

 

Paperport or some such program often causes that issue.