how to kill a program in openSUSE

[salvage]

Hi,
I've just started to use linux.Sometimes I would meet a problem:The program,for example, lumaqq,or yast2,just stopped there and do nothing.When I tried to close it,it seems that they cannot be closed,neither.However,I can do other things,such as using the firefox,open a new shell window,etc.But I cannot logout or shut down the computer.
I've tried to use xkill,and it does work.The program is closed,but I can still not logout.
Can anyone tell me what should I do to close the program properly?
Thank you very much.

[gogalthorp]

list the running processes wit

ps -A

You can see process eating CPU with

top (note: can be stoped with crtl-c)

to kill a process find it's PID (see above)

kill thePID

How ever it may be something more critical is happening. Do you see a lot of disk activity and a general slowing in these situations? If so you may have some bad sectors on the disk. You would then need to do a low level scan. I use SpinRite but it is not a free program. You can usually get a free disk scan/fix program from the disk manufacturer.

[salvage]

Thank you very much.
I think maybe xkill is more suitable for me.I wait a few seconds,sometimes a few minutes,and then the process is closed correctly.
What a shame!!!!!!