ti 89 titanium calculus malfunction

I've got a ti 89 titanium and one of its many valuable qualities is its ability to integrate and differentiate.

However, just recently, it have not been functioning correctly. When I try to calculate indefinite integrals or derivatives, my calculator returns a number instead of an expression.

__Ex__:

entered ∫xdx

keystrokes:[2nd] [∫] [X] [,] [X] [)]

returns: 25/2

entered d/dx(x^2)

keystrokes:[2nd] [*d*] [X] [^] [2] [,] [X] [)]

returns: 10

The calculator should be returning expressions involving the variable in question. I have no equations in the y editor, no programs that I have created or are aware of that might cause this and I have tried removing all the batteries with the idea in mind that it might reset the defaults. No luck.

Any suggestions?

Thanks