Modules showing up on *some* pages where they shouldn't

[flicman]

Hi there-

I'm running a relatively well-modified VirtueMart 1.1.x shop atop Joomla (found at http://www.shoehardware.com), and I'm having a strange problem that's been going on awhile.  I have modules assigned to only show on the home page, but they show up on some (but not all) product pages, to.

Here is a page where the two modules are displaying where they shouldn't:
http://www.shoehardware.com/tools.html

and here, a product page that looks right:
http://www.shoehardware.com/blister-care.html

I've looked at the configurations of the two pages and they're identical, but there must be something that I missed somewhere.  Any help that you can give me on this weirdness would be much appreciated - I'm at a loss, and haven't found anyone else here or elsewhere who has this same issue.

Thanks!

[Forrest]

Likely you have a VM itemid issue. Turn off your SEF and look at the itemids!

[flicman]

Thanks for the input - disabling SH404SEF does solve the problem.

I wonder what the problem with SH404SEF's re-writing causes the problem.  I'd really like to be able to use SEF URLs on the site, but I'd also like the site to look right.  Maybe too much to ask.

[Forrest]

You likely have an Itemid issue.

You should have a VM master link to your store, with the lowest Joomla itemid of any other VM links.

[flicman]

Turns out that this didn't solve the problem at all.  In fact, the only-homepage modules are showing on a bunch of new pages now.

I don't understand what an itemid issue is - my categories have ids, but there are 8 level 1 categories and nothing above that because that's how my navigation works.  In the Module Manager, mod_virtuemart is disabled altogether, but enabling it doesn't solve the problem, and creates problems with my layouts.

I'm so confused.  Clearly not too smart, either.