any soultion for GTA 4's random freeze and portal2 big exclamation mark??

hi, i have done the research already, i have done everything.
still doesnt work. im at kmeaw3.55 multiman 4.14

GTA 4's randomly freeze..i have tried turn off the autosave, reinstalll the game data into the HD.

and
portal2, after i load the game there a huge exclamation mark on the screen like this:
http://i.ytimg.com/vi/po6PNCqCZwQ/0.jpg

i have tried game disc load, bd mode and both together at the same time.
still got the same result...

and suggestion?

:miserable: