getting "not enough memory" when loading families

[vanderloo5]

I'm running xp pro64, 150gb hard drive, (132gb free space), dual core processor, 4gb ram. occaisionally when I go to load families I get "this computer does not have enough memory to load [such & such] family"
Running Revit 2009 64 bit. No other programs open. Don't even know where to start??? Does anyone have any suggestions? Already un/reinstalled revit.
Thanks,
Phil

[Scott D Davis]

Go to task manager and see how much RAM is being used without Revit open. Vista 64 takes at least 2 Gigs of RAM just to run. How many other things are running in the background? How big is the Revit model that you are using? There are many factors, but it sounds like you are simply hitting the limits of 4 gigs of RAM ona 64 bit machine.