Now that I am back from a wedding, I can resume my modem debugging. As I said 
previously, I've tracked down the source of the mysteriously changing 
/dev/ttyS3 permissions to ppp itself. When I use kppp or wvdial, the 
permissions are crw-rw---- until ppp starts, at which point the permissions 
change to crw-r-----. /etc/ppp/options reads as follows:
---
asyncmap 0
crtscts
lock
hide-password
modem
noipdefault
proxyarp
lcp-echo-interval 30
lcp-echo-failure 4
noipx
---
	For the record, I'm running Debian Sid, although if this and the KDE font 
madness continues, I'm going to start looking at Gentoo.
	:Peter