The sound cutting out indicates some other program has popped up a window
(which you can't see because it's hidden behind GPL's window) and grabbed
focus away from GPL. This other window is probably a dialog box saying
"You've been idle for a while, so I've disconnected you from the Internet.
Would you like to reconnect?", or some such. I believe that Windows'
notion of "idle" is rather, ahem, misguided, and it's closing your Internet
connection. Error 10049 means "address is not available", which fits
nicely with the fact that your modem disconnects.
On Win95 (translate if necessary on Win98)...
Double click "My Computer".
Double click Dial-Up Networking...
Right click on your Internet connection, and select Properties.
In the Connect Using box at the bottom, hit Configure.
Select the Connection tab.
In the Call preferences section, make sure "Disconnect a call if idle for
more than N mins" is NOT checked.
Just be sure to manually disconnect when you're done, lest you run up
unexpected connect charges.
Randy