Thank you for your reply. I don't think a size limitation is the cause (in my case), though. An example of a command that fails in a document, I'm working on now, is the following:
Which will throw this error:
Error, tables cannot be mixed with other container objects in an elementwise operation.
There are no functions defined on x and y, just a 4-element matrix multiplied by a 2-element vector. So the internal representation of either the matrix or the vector on the right hand side must be malfunctioning.
Whenever this happens, I can take the command from my large document and copy it into a fresh doc and execute and no errors will be thrown.