Why does my office's pc acts like this?

[iori57]

in the office, all other pcs can use "net send" to send instant message to each other, however when i try to use net send in my pc, it says
'net send xxxx hi' is not recognized as an internal or external command, operable program or batch file.

if you don't know, typing 'net send xxxx hi' in the command prompt will send the message "hi" to xxxx where xxxx is the computer id / user id depends of the network (in my uni they use computer id)

any idea how to fix this? thanks

 

[montag451]

Can you receive messages?

 

[nanaki333]

do you have the messenger service enabled on that computer?

 

[iori57]

i can't receive messages from other people too

messenger service is enabled

i also noticed that some of the suppose to be global commands don't work on my pc

for example other pc can use kapw.exe (i duno wat it is though) in C:\> although the kapw.exe is actually located somewhere else but not in C:\>, but when i try to use it on my pc it gives the same error message 'kapw' is not recognized as an internal or external command, operable program or batch file.
Does this tells anything?

thanks again