Well even though I don't think PCSX2 will run on your computer heres what you do...
In the Configurator slect the CDVD option and hit configure.
Now select your iso where it says to selsct it and then hit run CD/DVD.
Also note this!!!!!!
Sometimes if you restart your computer it will owrk or simply log off and try that above methos again. Let me know how you get on.