(vantage) freeze up

Im having a problem in Inventory management. I have a user that can
add a purchase order Under Inventory Management, but if he stops
using it for a shot period of time or minamizes it for a short period
of time it freezes up on him and he can not add any purchase orders.
He then has to CTRL-ALT-DEl to get out of the window. He used to have
this problem only when his C:\vantage work folder was pretty full. he
would just delete the contnents in the folder and that would fix the
problem for a while, but he may only have 3 things in his folder
before he has to delete it. Im kinda new to vantage, so if anyone can
help me please do. Thank you,

Pete Juratovic
Sabina Manufacturing
Pittsburgh, PA