I've solved this problem by doing (almost) what the last guy said:
press windows key + R (runs the 'run' dialog box)
go to boot tab
go to advanced settings
(here's where it's different)
UNTICK BOTH 'no. of processors' and 'max memory'
these both default to the system max anyway so when you untick them then you put no limits in.
I went from 1.5BG available (out of 6!!) to 5.8GB available.... nice.
And now my music software runs like a dream!!