Please provide more information about the problem - IDEA version you are using; how are you trying to use copy-paste ('Ctrl + C' + 'Ctrl + V'/'Ctrl + Insert' + 'Shift + Insert' etc); check if copy-paste works via 'Edit' menu; check if it works in other applications; try to reproduce the problem at another machines etc.
'Copy-paste doesn't work on Windows XP' may be not the best way to report a problem as there are thousands of IDEA Win XP users that use that functionality just fine.
Please provide more information about the problem - IDEA version you are using; how are you trying to use copy-paste ('Ctrl + C' + 'Ctrl + V'/'Ctrl + Insert' + 'Shift + Insert' etc); check if copy-paste works via 'Edit' menu; check if it works in other applications; try to reproduce the problem at another machines etc.
'Copy-paste doesn't work on Windows XP' may be not the best way to report a problem as there are thousands of IDEA Win XP users that use that functionality just fine.