Topmenu item disappear

Hello,
Sometimes item in the topmenu disappear (just one, not all; apparently without a reason), does anybody know what this could be?
To have it appear again, I have to click on the menu item, in Joomla administration and Save it, without change anything.
I'm using Joomla 1.6.3, with the lastest version of CB.
Thank you.

What version of funlite?

1.0, sorry I forgot to say it. I've upgraded it to 1.1 now, but the problem is still there, maybe it is Joomla 1.6 cache system?

Ah, I've also noticed some not important things, in the file html/mod_menu/default.php, last lines: I think the span should be: </span>

And, in the same file, probably <ul id="nav should be <ul class="nav, at least for what validator.w3.org/ is saying.

I answer my self, it seems Joomla's 1.6 cache, if I disable it, I have not this problem.
If you know the reason or a fix it would be good, else I will disable it, thank you very much.