I turned on my 01 C5 vette and got a warning to service my ABS.
Active Handling System. It kept flashing on my screen, so I shut the
car off and restarted and everything ok. Does this mean I need to
have it looked at or is this just a computer malfunction.

I would get it checked out!!! Just not something that I would mess around with!

disconnect the battery for 5 mins so the computer resets.. then if it comes on again you probably want to get that checked out. hope it helps.. keep us updated

Thanks for advice, but so far I have done nothing but ignored it
to see if it comes back on. I have run the car and everything is working ok. If it continues then I will pursue further.

I Had The Same Warning Come Up On Mine. After A Few Days The Brakes Were Soft And The Message "brake Fluid Low" Came On The Screen. I Took It To The Dealer To Be Serviced And It Turned Out To Be I Had A Pin Hole In My Brake Line. Not Sure Why The Message Started Out About The Active Handling But That's What Happened. You Might Want To Check The Brake Fluid. Good Luck.