Modem freezup

[ktb <ktb@binary.net>]

  Every once in a while my modem won't respond to "pon"  I have
tried to see a pattern in the freezeup but haven't found one.  I ran
plog after the last incident:

~$ plog
Jan 28 13:34:13 XYF chat[830]: expect (OK)
Jan 28 13:34:35 XYF pppd[840]: pppd 2.3.5 started by kent, uid 1000
Jan 28 13:34:35 XYF pppd[840]: Device ttyS0 is locked by pid 829
Jan 28 13:34:35 XYF pppd[840]: Exit.
Jan 28 13:34:58 XYF pppd[829]: Connect script failed
Jan 28 13:34:58 XYF chat[830]: alarm
Jan 28 13:34:58 XYF chat[830]: Failed
Jan 28 13:35:04 XYF pppd[845]: pppd 2.3.5 started by kent, uid 1000
Jan 28 13:35:04 XYF pppd[845]: Device ttyS0 is locked by pid 829
Jan 28 13:35:04 XYF pppd[845]: Exit.

I see the message says the modem is locked up by "pid 829"  but I have
no idea what that means.  This happens only once every few days but when
it happens I have to do a complete shutdown to get the modem to work
again; a reboot won't do it.  Anyone know how to deal with this?

Here is plog when I can hookup, if it helps:

$ plog
Jan 28 13:47:19 XYF chat[231]: ATDT4848144^M^M
Jan 28 13:47:19 XYF chat[231]: CONNECT
Jan 28 13:47:19 XYF chat[231]:  -- got it
Jan 28 13:47:19 XYF chat[231]: send (\d)
Jan 28 13:47:20 XYF pppd[230]: Serial connection established.
Jan 28 13:47:21 XYF pppd[230]: Using interface ppp0
Jan 28 13:47:21 XYF pppd[230]: Connect: ppp0 <--> /dev/ttyS0
Jan 28 13:47:21 XYF pppd[230]: sent [LCP ConfReq id=0x1 <asyncmap 0x0>
<magic 0x5fcf> <pcomp> <accomp>]
Jan 28 13:47:22 XYF pppd[230]: rcvd [LCP ConfReq id=0x1 <mru 1500>
<asyncmap 0x0> <magic 0xb7f84692> <pcomp> <accomp> <auth pap>]
Jan 28 13:47:22 XYF pppd[230]: sent [LCP ConfAck id=0x1 <mru 1500>
<asyncmap 0x0> <magic 0xb7f84692> <pcomp> <accomp> <auth pap>]

Thanks,
Kent