error compiling

I have an uno and have successfully uploaded the software on my laptop. I want to use it from my desk top so I have downloaded the programme, run it, plugged in the uno, written a program and tried to upload it .I get

avr-g++; CreateProcress: No such file or directory

in the box at the bottom I have tried the same program on my laptop and it works. I even loaded the bare minimum program from the examples on the desk top with the same massege. I have checked all the settings are the same as the laptop (with the one difference, I am using com3 on the laptop and com4 on the desk top) ie UNO AVRISP MkII etc. I have done the loopback test suggested above and it works so I know the uno and the port are ok. Can anyone tell what I am doing wrong? Thanks, Bob.,118440.0.html