"Object invalid or no longer set"

[Damian_nes]

Often, when searching for specific records within a form,
I will receive one of several messages, including "Unknown
function name" (this often appears first), "The expression
is typed incorrectly, or it is too complex... (etc)",
and "Object invalid or no longer set".

What I don't understand is why these error messages only
appear after the form has been running for a few minutes.
For a while it runs perfectly fine, but once I start
getting these error messages several fields in my subforms
will be replaced with #Name? instead of the correct
values. (The "Object invalid or no longer set" message has
to be closed for every field this happens to)

This doesn't seem to be a result of calling a flawed
function because it's usually triggered just by switching
to a new record. I don't believe I've ever made reference
to the CurrentDb function so I don't think it's a matter
of correctly declaring a database variable somewhere. The
links to the source fields are fine, as proven by the fact
that the form runs perfectly for a little while, even when
switching records.

Does anybody have any ideas why this is going on?

Damian