Dual boot G4: internet fails in OS 10.3, but perfect in 9.2.2 - please help

Question

Please bear with me if this is a little muddled, but I'm so fed up now that I'm not sure of my own logic any more!
I acquired, months ago, a dual boot G4 tower which was running the 10.3.9 update and 9.2.2 . It had been upgraded with faster processor and lots of RAM, and everything seemed to be working perfectly - and FAST - except the internet in OS X. After lots of reading and realsing that other people have had similar symptoms (silly messages from Software update, dropped connections after a few minutes or even seconds, many failed connections, most websites startting to load, and then failing followed by a disconnect), I tried everything suggested, to no avail. OS 9 on the same computer works fine, so the modem is ok. A G4 titanium laptop (10.2.8) also works fine with identical settings to the tower and using the same connecting lead, and a PC running XP Home also works perfectly, so the line must be ok.
So - it must be Panther - right? In desperation, I did an erase and install of 10.3.1, thinking it must be something to do with the update (the guy I got it from confirms it was working fine when it left him - he downloaded the 10.3.9 update on the same machine - and I do believe him). But nothing has improved, and I'm tearing my hair out.
Sorry this is so long, but I thought I'd try to provide all information in the one hit. I'd be very glad to hear what you all think, and what I can try next?
Thanks.

Answer 1

Welcome To  Discussions tchaik!
No guarantees, but try this procedure.
Quit the browser and disconnect from the Internet.
Navigate to: HD > USERS > YOUR HOME > LIBRARY > PREFERENCES
If present, move to Trash:
com.apple.internetpref.plist (a file)
com.apple.internetconnect.plist (a file)
com.apple.internetconfig.plist (a file)
Open System Preferences > Network >
Location: Select "Automatic"
Show: Select "Internal Modem"
On the PPP screen, click PPP Options. UNCHECK ALL options
On the TCP/IP screen, Configure using IPv4: Select "Using PPP"
On the Modem screen, Select your modem from the list. I'm using an iMac (Summer 2001), and I have "Apple Internal 56K Modem (v.90)" selected.
Check;
"Enable error correction and compression in modem"
"Wait for dial tone before dialing"
"Dialing": Tone
"Sound": On
"Show modem status in menubar"
Also select your Country.
Then:
Location: "Automatic"
Show: "Network Port Configurations"
Make sure "Internal Modem" is checked and at the top of the window.
In each of these panels, after you have made your selections or changes, be sure to click on the "Apply Now" button in the lower right corner, if it's available.
What ISP do you use?
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