Corrupted Data
Corrupted data can result from using cheats or cheat-enhancers, such as Gameshark or Action Replay. Corrupted data can also occur from the power cutting off while saving or removing the memory card while it is in use. To fix this problem, power the system up without any software or DVDs, and enter the memory card management screen. Deleting the file that is corrupted should clear things up, but if it doesn't, you might have to completely clear the memory card of all save files.
Third-Party Memory Card Problems
As a general rule, use officially licensed first-party products to use with your system. This means that the products are either made by Sony or they are licensed to be used with your PlayStation 2. When using third-party accessories, there are a number of possible problems that can occur. Files are more likely to become corrupted and some games might not even be compatible with certain memory cards.
Sometimes, the memory card may not even fit into the system's memory reader, in which case you should check for any loose screws or call the company that produced the card for more information. While the first-party gear might be a few more dollars, in the long run, you'll probably be thankful you paid the extra money.
Other Problems That Might Arise
If your game isn't saving, make sure you are doing it correctly and not accidentally hitting the cancel button during saves. If the game still won't save, try another game to see whether it's the game or the card. Copying files from one card to another might also present a problem, if so, try reformatting the card and trying again. Sony memory cards come with a 90-day limited warranty from the purchase date, and they can be sent in for repair. Third-party memory cards' warranties vary, but most include some type of satisfaction guarantee or warranty.