At approximately 1pm (GMT) today, whenever I clicked on a Virtuemart link on my site it would return an error. Although I can't remember what the error said, it was related to Line 233 on com_virtue.php (or something like that). After disabling Joomla search engine friendly URLs, the site seemed to work, but I ended up with Virtuemart's usual long URLs.

What solved the problem for me was noticing there was an update to the Virtuemart SEF extension I purchased from Artio. As soon as I have done the update, it worked fine for me and my site was back up and running.

What is worrying is that is this kind of thing going to happen frequently? Will JoomSEF be updated and totally bring my site down, without me noticing?

Many thanks,

Well,

JoomSEF does not upgrade alone. And if you upgrade JoomSEF component, you should also remember to update all available extensions and vice versa.

The error you are talking about was most likely caused because you did not have latest version both of JoomSEF and VM extension.