If its multiple games, and freezing at seemingly random times during games, and not at the same location each time, then it is most likely the hard drive.
However, the most common cause of ps3 game freezes is corrupted data. To fix this you will first need to go to the "game data utility" menu. Find the game that is giving you problems, press triangle and select "delete". This will not delete any saved data, don't worry.
When that is complete, you will need to turn off your system, and boot it in safe mode. Here's how to access saffe mode:
1st. Once the system is off, press the power button and HOLD it. You will hear one beep for the system turning on, keep holding, a second beep will denote a video reset, keep holding. Lastly the third beep will tell you the system has turned off. Now you can let go of the power button.
Next, you will do the above process again. Hold the power button down. The first beep is the system start, keep holding the power button, 3 seconds later it will beep a second time for video reset, keep holding it. A few seconds after that, if done correctly, you will hear a quick double beep. The system will now be in safe mode.
You will nerd to plug the controller in using the usb cord to proceed. Once that is done you will see a black screen with white text. It will lust I think 6 options for you to choose. You will want to choose the third Inez restore file system. Once again this will not delete any saves.
The system.will tell you there are corrupt files on the hard drive and that it can take up to 3 hours to repair. Don't worry, it wont take 3 hours lol. Once theprocess is finished, the ps3 will restart and you will be taken to the normal xmb menu.
All you need to do now, is pop in the game, and reinstall all the update data again.
Corruption has happened to me on gt5 and uncharted 3. The cause? Undoubtedly it was from a loss of internet connection during the download of an update or dlc. Now I have a very strong WiFi connection, but all it needs is a half second of no connectivity to screw up the whole game.
I have since gotten an 80 foot long Ethernet cord, which I now run through a hole in my ceiling and plug directly into my router. I have never had a corrupted game file since, and my freezing problems went away (except in skyrim because, well you know its skyrim for ps3)