This guide will help if you're having 'Low memory' problems with the Galaxy Ace. Here's a few steps to help you fix the low memory problem.
From your Apps list, go to Settings > Applications > Manage Applications.
Tap All at the top of the screen.
Scroll down to Contacts Storage.
This should usually be only a few hundred kilobytes (KB), if it’s more than a few megabytes, there could be a problem.
Fixing the problem isn’t as straightforward as just deleting the data from the app because this could wipe your contacts from your phone. Before deleting anything, make sure your contacts are backed up first. If they’re already in your Google account then you don’t need to worry, if not then you can back them up to your SD card to keep them safe.
From you Home screen, open the Contacts app.
Go to Menu > Import/Export.
Tap Export to SD Card, then confirm by tapping Yes.
This will add a copy of your contacts to your memory card. We can restore this file after we've fixed the memory problem.
Now that you've backed up your contacts, it's safe to delete the contact data stored on the phone.
Go to Settings > Applications > Manage Applications.
Tap the All tab at the top of the screen.
Tap Contacts Storage > Clear Data.
Reset your phone by holding down the power button, and tapping Restart.
If you've set your phone to sync with your Google account, your contacts should re-appear when you turn the phone back on. If you backed them up to an SD card, here's how to restore them.
Open your Contacts app, and tap the Menu button.
Choose the Import/Export option.
Press Import from SD Card.
You can choose to either import them to your Google account or back to the phone memory, tap either Phone or Google.
Hopefully that's you sorted, but if you need more help, you can get in touch with a Team Knowhow Expert here.