inputs always high pic16f628a

hey im trying to read my RB5,6,7 ports with interrupt on change my trisb is equal to 11100001 but for some reason the inputs arent always low.. they are giving random values.. specially RB6 and 7.. do i have to drive them to ground through hardware? but then switching is going to be hectic. or could this be something wrong with the software?
i double checked my board to see if it could be something wrong with my circuitry but without my PIC installed its showing 0V but once i install the pic its showing 1.8-0.8 volts random values.
please help

Enable the weak pullups on PORTB

oh thanks but what is weak internal pullup? what does it do? and how do i enable it?

Off the top of my head search the datasheet for RBPU and clear the bit. It should be a bit in the OPTION register.

hehe ok thanks