hp35s vector input bug semi-workaround?

[pkh]

...and one more thing,

if you find that you suddenly start getting the error when you already have two 2-D vectors entered into the stack, then clear the entry that causes the error, roll down the stack (with R-down), and do a dot product on the stack entries, it calculates the dot product correctly, but still won't accept new vectors input.

It's as if it starts to have difficulty accepting new vector inputs, maybe difficulty understanding the comma?