This can occur for three different reasons.

1) You may have low memory on your machine. 
- Please make certain you have enough free memory.

2) If a text item contains all three quote characters ( ' " ` ).
- Please check your text boxes so that they do not contain all three items.

3) If any of the pages you attempt to save are completely blank page (ie: no items on a page whatsoever). You need to look at each page in your site to confirm that there is 'something' on each page. Otherwise the software will see this as a potentially corrupt page and stop you from saving it.
- In this case, the solution is to add some item to each page in your site prior to saving it.