My magento website is one of a multistore on magento 1.6.2 on a shared server. Suddenly today the URLS (SEO friendly) in subcategories stopped resolving. Querying this with the hosting company, they told me that they had upgraded their litespeed version on the server which coincided with the errors. They have promptly rolled back to the previous litespeed version which has fixed the issue. However, this is to give me some breathing space to get it properly resolved. This was their advice: "You might want to get your dev team to check the installation to ensure it isn't set up in a way where it works only with older versions of LiteSpeed. You might want to get them to ensure the site is set up so it works with the newer versions too".
Does anyone have any insight into what I should check first? Advice greatly appreciated. Thanks Darren.
edit: I've just been told by the hosts that the Litespeed version is currently 5.2.2 and the update version is 5.3.6