Sounds like you need a neighborly discussion to find out just what she believes is a problem. Could be anything.
I've worked in towns that dont allow parking in the "front yard" (meaning between the property line and the front building setback line, not necessarily where your house is). Some upscale developments may have similar restictive covenents in your property deed, driven by "keeping up appearances".
Call your town planner, or stop by town hall to look at the zoning regs. Most libraries also keep local regs on hand.