Out of Memory in Access application

I have an Access application, that open up with a main form and remains open till the application is closed. I also have lot of other forms on this application, and each form consists of list boxes, text boxes and command buttons.
In the morning the application works fine, but towards the end of the day when I click on a command button to do something I get a memory error (out of memory).
I'm using recordset objects, but I'm closing every one of them and setting it to nothing.

I'm jumping in and out of forms. I close the form when I get out of it. So what could be wrong, what is happening when the application remains open for a long period of time? How could I free the memory ??

Reggie