PIC24H interrupt timing

// Timer1 interrupt handler
void __attribute__( ( interrupt ) ) _T1Interrupt( ) {
    flag1 = 1;
    flag2 = 1;
    IFS0bits.T1IF = 0;
}

while ( 1 ) {
    IEC0bits.T1IE = 0;  // Disable Timer1 interrupt
    f1 = flag1;
    f2 = flag2;
    flag1 = 0;
    flag2 = 0;
    IEC0bits.T1IE = 1;  // Enable Timer1 interrupt
    if ( ! f1 && f2 ) {
        // what's up!?
    }
}