memory useage issue

HelloI have 737PIC, Level-D 767 and now PMDG 747, well, the PMDG keeps clocking up memory useage and no doubt if I fly for a few hours it might all run out, whcy is this and is there a solution?It starts at around 330k, with other planes it stays around that figure, with PMDG it hits 600k within 30 mins.I have MCE 2005I have just installed KIS 2009, just upgraded from 7, I don't think its the virus scanner as it only affects PMDG.krishan