SW 2009 runs out of memory

i am running SW 2009 sp3.0. every so often i get the message"SW cannot acquire the required memory and is terminating"

thing is, when i chakc the task manger before i hit OK, it says I'monly using 1.5 Gigs of the 4 Gigs i have installed.

any reason why Sw cannot 'acquire' the additional 2 gigs on thesystem?


thanks

TomSolidworksAdministration