On 2007.07.26 10:33:15 -0600, Brian de Alwis wrote:
> Were you viewing any files using an external viewer?  I've found
> that Firefox often `hangs' when opening a second PDF using xpdf --
> until I quit the other xpdf instance.

This pdf-viewing hang just happened to me and it appears to have
the same symptoms of parked processes.

$ ps sw | sed -n -e 1p -e '/firefox/p'
 UID   PID  PPID  CPU LID NLWP PRI NI   VSZ   RSS WCHAN   STAT TTY      TIME COMMAND
1859   923     1    0  43    9  28  0 63604 91768 -       ZW-  ttyE0 0:00.00 /usr/pkg/lib/firefox/firefox-bin about:blank 
1859   923     1    0  26    9 -14  0 63604 91768 parked  DW   ttyE0 0:00.00 /usr/pkg/lib/firefox/firefox-bin about:blank 
1859   923     1    0  11    9 -14  0 63604 91768 parked  DW   ttyE0 0:00.00 /usr/pkg/lib/firefox/firefox-bin about:blank 
1859   923     1    0  10    9 -14  0 63604 91768 parked  DW   ttyE0 0:00.00 /usr/pkg/lib/firefox/firefox-bin about:blank 
1859   923     1    0   6    9 -12  0 63604 91768 parked  DW   ttyE0 0:00.00 /usr/pkg/lib/firefox/firefox-bin about:blank 
1859   923     1    0   5    9 -12  0 63604 91768 parked  DW   ttyE0 0:00.00 /usr/pkg/lib/firefox/firefox-bin about:blank 
1859   923     1    0   3    9 -14  0 63604 91768 parked  DW   ttyE0 0:00.00 /usr/pkg/lib/firefox/firefox-bin about:blank 
1859   923     1    0   2    9   2  0 63604 91768 poll    DW   ttyE0 0:00.00 /usr/pkg/lib/firefox/firefox-bin about:blank 
1859   923     1    0   1    9 -14  0 63604 91768 wait    DW   ttyE0 0:00.00 /usr/pkg/lib/firefox/firefox-bin about:blank 

`ktruss -di' on the firefox process shows:

   923      5 firefox-bin gettimeofday(0xb93fff0c, 0) = 0
   923      6 firefox-bin _lwp_park(0xb93fff04, 0, 0x8d3c58c) Err#60 ETIMEDOUT
   923      6 firefox-bin gettimeofday(0xb91fff1c, 0) = 0
   923      5 firefox-bin _lwp_park(0xb91fff14, 0, 0x8d3c68c) Err#60 ETIMEDOUT
   923      5 firefox-bin gettimeofday(0xb93fff0c, 0) = 0
   923      6 firefox-bin _lwp_park(0xb93fff04, 0, 0x8d3c58c) Err#60 ETIMEDOUT
   923      6 firefox-bin gettimeofday(0xb91fff1c, 0) = 0

which continues repeating ad nauseum.

This is an older Firefox 2 and somewhat -current:

$ pkg_info -I firefox
firefox-2.0.0.3nb1  Lightweight gecko-based web browser
$ uname -a
NetBSD monolith 4.99.22 NetBSD 4.99.22 (LAPTOP.MP) #0: Fri Jul  6 11:05:04 CST 2007  bsd@monolith:/usr/obj/sys/arch/i386/compile/LAPTOP.MP i386

Anything else I can do to help provide more information?

Brian.

-- 
  Brian de Alwis | Software Practices Lab | UBC | http://www.cs.ubc.ca/~bsd/
      "Amusement to an observing mind is study." - Benjamin Disraeli