Wow, HD5770 at 1366x768 is an overkill.
Anyway, what is your FULL specs? CPU? RAM? Mobo? PSU?
Are you sure 6pin power connector is properly attached?
You said that only cricket and spiderman are your problem, seeing the other games are fine then I think you have problem with the game itself (cricket and spiderman).
Iam using a
core 2 quad Q8200 2.33 Ghz
2Gb DDR2 Ram
500w coolermaster PSU
For the 6pin power connector I ve checked it and it is fine and properly connected.
Iam using the card in a pcie-16 x1 slot could it be causing problem?