I have 2005 330 ATP, I noticed that my front brakes squeak and when that happens my hand brake gets harder and harder to squeeze to the point that my front wheels lock up completely.
When I release the brake line at the master cylinder to release the pressure, I have brakes again. But the problem starts all over again.

 

Check the front pads for excessive wear. If worn the pistons can push out further than needed and can stick.Plus they can just stick over the years on their own over the years. Seal kits are available for these.If you eliminate these as a problem then try brake bleeding. Mityvac makes this a simple job to get rid of any air pockets that can cause problems also.If you continue to have problems could be the master cylinder piston itself sticking and may need a new piston kit. 2005 Polaris ATP 330 4X4 (A05JD32AA) Controlsfront Brake | Cycle Parts Warehouse