Zyxel G-220 will not connect after a period of time.

I've got the Zyxel G-220 working with XP. I connect up to the wi-fi being broadcast in my area (linksys, primarily). After a few weeks, eve though I am getting a signal shown, the connection will go down due to 'limited connectivity'. Taking out and reinstalling the software will not correct the problem, nor will System Restore. My PC allows me to rioll it back to 'factory-fresh' yet retains my installed programs and data. Only by doing this can I get the wi-fi to work again. To avoid the extra hour or so to reinstall whatever the 'system recovery' changes, how can I get this adapter to stay working? Thank you.