Samsung Galaxy Ace Internal Memory Problems - I, like so many others, found that after 2 months I had Internal memory running low messages. I have very few applications other than those originally provided, I had cleared all the cache, messages, history etc. but still my internal memory was down to 16 MB. Then I noticed that when you go to Settings - Applications - Memory Usage that right at the top my Email (NOT G-Mail) registered at an extremely large Data - 75 MB!!! I had no locked or saved messages, so it became obvious it was hanging onto previous unwanted data.
I deleted it and voila I had 90 MB of Internal Memory back. WARNING: You have to reset up your e-mail account so take a note of your account settings before you delete. I don't really use G-Mail but suspect that a similar thing may occur with that because ALL the Google Apps - Playstore, Books etc. all take bits of memory you could well do without them doing!! Hope that this might help somebody somewhere OR if someone knows how to stop it happening in the first place - TELL US!