Yes there is. Its a DNN core problem that will be fixed in DNN 5 (DNN core says - haven't tried it out myself yet in DNN5.0R2).
You should never set the cache timer under 120 sec. Anything less and strange things starts happening. Most of us has it set to its default value at 120 sec.
Tell your user in a text-box, to "Allow a 2 min wait". In most cases it's really just a few seconds, but some times it takes the full 2 min.
If you have 1000s of users, on a slow server, you also might see caching at 5-8 min.
Let us know how it worked out,
/j