urls stop working

Hi, I keep getting an annoying problem which i can't work out why it's happening.

SEF Advance is working fine, then if for example the page that it is being redirected to is not available for a brief moment (such as when I am uploading a new version), I am redirected to the home page.  This is fine because I don't have a custom 404 specified.
But if I get redirected to the home page, I can never use that SEF url again.  It is like it is caching somewhere that this page isnt available, so don't bother ever trying again.
How can I fix this when it happens??

thanks.

It's maybe just cached in your browser? Empty your cache or try another browser.

unfortunately it's not that simple (i've tried other browsers (and computers)).  Here's a link to the url in question - www.4x4earth.com.au/tracklist

It's not the first time this has happened... it's happened quite a bit, and i've had to create a new alias's, but that's not really an option this time.
I've duplicated the alias as, www.4x4earth.com.au/tracklisttest so users can still get to the page until this is fixed, but I need to know why sef advance does this... ?

thanks
Gavan

Any ideas?  I've had this happen on two different sites I run.

Do you use caching in SEF Advance?

No, I haven't enabled that.

cheers,
Gav