Instructions
Check that the Max Memory Stick is correctly inserted into your PSP's system memory. Many PSP memory errors are caused by incorrect or loose media insertion. Open the PSP's MemoryStick storage cover on the left side of the system. Remove the Max Memory Stick and securely reinsert it, label side facing the nonscreen face of the PSP.
Connect the PSP to your PC via USB. Turn on the console and select "USB Connect" from the System menu. Clear unused movie or audio data from your Max Memory Stick to free up space by selecting the data, right-clicking and choosing "Delete," right-clicking the "Recycle Bin" on your computer's Desktop, and selecting "Empty Recycle Bin." Clearing space on an overfilled Max Memory Stick can fix slowdown or file read errors.
Remove corrupted data (data that will not load on your PSP's menu or games) from the stick to prevent further corruption. Connect your PSP to your computer with the system's USB cable. Navigate to the corrupted data, right-click and select "Delete" to clear the corrupted data and preserve the contents of your Memory Stick.
Reformat a Max Memory Stick from which no data can be loaded or recovered by the PSP. Connect your PSP to your computer via USB. Copy all data on the system to a folder on your desktop, and then disconnect your PSP by pressing "O." Navigate to the "Settings" menu and open the "System Settings" section. Select "Format MemoryStick" and press "X" to confirm. Your Max Memory Stick will be reformatted and should now work with your PSP. Data can be rewritten to the stick by transferring files from the folder on your desktop.