problems with popen (linux7.3 python2.2.2)

[Byrom, R (Rob)]

hi, 
When I use: 
os.popen('ssh -l root at something tomcat4 stop') 
I find the command always hangs. The 'something' host contains the correct
key in the authorized_hosts file and works ok on the command prompt. I've
tried os.system() but this also hangs. I notice that the 'tomcat4 stop' is
being executed but when I do a 'ps -ef' I notice the popen process is still
alive. I've also noticed this command sometimes works (ie it doesnt hang)
but I've no idea why. Has anyone experienced similar problems with this? Or
does anyone have any alternative suggestions? I'm really at my wits end with
this one! 
thanks alot, 
Rob