Jamie Lynn Spears' Daughter Maddie, Warnings and Lawsuits Over ATV

Jamie Lynn Spears' daughter, Maddie, probably should not have been a driver or a passenger in the Polaris that flipped over and critically injured her, and we've learned there's been a big problem with the company's ATVs rolling over.

The Polaris in question, the RZR 170, has an instruction manual which reads in part, "Never allow a child under age 10 to operate or ride as a passenger in this vehicle." There is a qualifier ... "Permit continued use only if you [the parent] determine that your child has the ability and maturity to operate safely."

Maddie is not close to 10 ... she's 8 years old.

We've also found lawsuits involving RZRs that flip over. In one case, the RZR -- not the 170 -- rolled and the metal portions of the roll cage pinned the driver's head and neck, fracturing his spine.

There's another case in which a RZR flipped and the driver was severely injured when the roll cage collapsed on her.

We contacted the company that appears to have sold Maddie's family the RZR 170, but they had no comment other than to offer prayers to the child.

A spokesperson for Polaris tells us, "The safety of our riders is our absolute top priority. Our thoughts and prayers go out to the family."

TMZ broke the story ... Maddie was critically injured Sunday when her RZR flipped over and submerged into a pond, trapping her underwater for several minutes as her mother and stepfather frantically tried to remove her seat belt.