Need some advice please gents

Just got back on a bike for the first time in 8 years, need to commute quickly to work, bought a 1999 Fazer 600, 1800 miles, well cared for etc etc....

My last bike was an R1 and before that a ZX6R, when you took your hands of the bars for a stretch etc, the bike ran straight and well balanced at low speed.

BUT this fazer is a little scary....below 40mph, if you take your hands of the bars, it instantly starts slapping, within a few swings it is full violent lock to lock. Never had any bike ever do this before.

Your thoughts ????

Leigh