Out of stack space
Too many active Function or Sub calls. Check that recursive procedures, both event and general, terminate and that they are not nested too deeply.
A cascading event will cause this error.
Local variables (which are stored on the stack) require more local variable space than is available. Try declaring some variables at the form or module level instead.
User-defined types and fixed-length strings share space with the stack. Try redefining some of these in other ways that do not use static memory.
Arrays declared in procedures share space with the stack. Declare these arrays in a global module if possible.
Too many nested DoEvents.