Spontaneous permission changes

[Elmer E. Dow]

Greetings:

I'm running a multi-boot IBM R40 laptop (Red Hat 9, Knoppix and WinXP
Pro). I've been using wvdial to connect via a Linksys EtherFast 10/100 +
56k modem PCMCIA card. This evening when I tried to dial out I received
the message "Cannot open /dev/modem: Permission denied." I tried dialing
out as root and it worked just fine. So I checked the permissions on
/dev/modem:

ls -l /dev/modem
lrwxrwxrwx 1 root root 10 Sep 1 19:09 /dev/modem -> /dev/ttyS1

That looked OK to me, but when I used Konqueror to check permissions,
user had read and write permissions, while group and others only had
read permissions.

Using Konqueror, I changed the permissions to again give all read and
write permissions for /dev/ttyS1 and /dev/modem and everything's working
fine.I can dial out as user as before.

Why did the console and gui interfaces list different permissions?
And why did ttyS1 spontaneously change permissions -- at least as
reported by the gui?

Earlier this week I had a similar occurrence on the same machine using
Knoppix (installed on the hard drive -- it's basically Debian unstable)
and wvdial. I'll briefly report that, too, since there were some
commonalities and it may give a hint as to what's going on. On boot
cardmgr reported:

cardmgr [703] could not adjust resource:
   IO ports 0x2f8-0x2ff: Device or resource busy

The boot would hang until I unplugged the pc card modem, then it
reported: 

"Warning: no high memory space available. Unable to map card memory!"

Wvdial reported 

"Cannot open /dev/modem: No such device"

/dev/modem had disappeared, so I recreated /dev/modem and everything
worked fine.

Common to both occurrences was having Konqueror, Evolution or Kmail, a
console and multiple OpenOffice documents open. In the case of Knoppix,
I had shut down with these apps open, and they were reopening on boot
up. Could opening or having opened so many windows create these problems
by tying up too much memory?

Red Hat 9 reports in /var/log/messages:

0MB HIGHMEM available
255MB LOWMEM available

I can't see how lack of memory could affect the permissions or even
delete a symlink like this.

I'm open to any speculations that you knowledgeable folk may offer as to
what happened here and why -- and how to avoid having it happen again.
I'm no IT pro, just a desktop user.

Regards,

Elmer