Which version of DNN are you using, it looks like a 2.x version since it's calling an Access DB as the provider? Have you checked out your Access database and made sure there is no corruption? Is there a lot of traffic going to the site? If so, maybe you just reached a limit that Access will support.
Patrick: that's something I'm checking.
In the worst case scenario, I'll have to move all the access data into a SQL instance - but I'm not at all sure about the consequesces. For example - will all the Tab IDs still be ok? or are they derived from some auto numbers?
It's stuff like this that makes me ask for someone who knows their stuff with DNN (and can maybe help me upgrade to 3.0...)
Roy you should contact Cathal Connoly, he's one of the core members involve in DNN.
I send you his email !
Roy, you should definitely upgrqde to 3.0: skining, better separation of modules (you only load what you need), better perf, better managment, etc...