Msg : 'Error. Can't initialise plug-in's directory. Try again later.'

One of our users , had this message when he launch our NSIS Install.
'Error. Can't initialise plug-in's directory. Try again later.'

We didn't found anything specials in his configuration (WindowsXP)
Anyone have an idea ?

Thanks

2 ideas come to me:
1.- InitPluginsdir.
2.- The user don't have access to the temp directory, maybe is readonly that folder for him/her.