The reason why you can't create this page with that name is that these words are used for our folder which holds all the files for your site. As a result, the name Resources or Classes is reserved (can't be used) to avoid a conflict that would create an error on your site.
As a workaround, when you create the page, call it something other than Resources or Classes. Then use the Page Manager to edit the menu text to display the name you want on your navigation menu.
Here are the steps to take you through this process:
1. In your Sitebuilder, click Page.
2. Click on the pencil icon. A dialog box will open. Enter the new name for your page (not Resources or Classes).
Now you need to edit your navigation and hover text so that word Resources or Classes is reflected in your navigation. To do this:
1. In your Sitebuilder, click Navigation. The Page Manager will open up, with a list of all your pages.
2. Select a page and click Edit.
3. In the drop-down menu, you will see two boxes: Label and Hover Text. Label is the name that appears in the navigation menu of your site. Hover Text is the text that pops up when someone moves their mouse pointer to one of the tabs in your navigation menu.
4. Type your text into the boxes. Click OK.
Your navigation will be updated with the changes you made.