'kill -9' doesn't always work for me.  Because of the circumstances, I 
suspect a race condition.

I hae problems with a Verizon EVDO card; I posted about them a little 
while ago.  This note is about a problem when I try to kill pppd.

If, in the root window that's running pppd, I do ^Z and 'kill -9 <pid>',
nothing happens.  Not good, but not a big surprise; we've all seen 
drivers that wedge in the kernel.

If, however, I do the 'kill -9' from a second window, it works.  That 
suggests some problem about killing a stopped process, especially if 
it's slightly stuck on something todo with a device driver.

		--Steven M. Bellovin, http://www.cs.columbia.edu/~smb