I have noticed that about once a month, I will hover over an item to check it's value on the AH (I do a full scan of the AH every few days and a scan of rare+ daily) and all items will have a value of ?. It seems as though all of the saved data wipes itself every couple weeks.

Do you know a reason this might be happening?

Old version, not properly installed/updated, you updated and the update had an incompatible history, you accidentally deleted the savedvariable file ...

All seem to be viable reasons though from my experience it seems to happen at random when I have not touched any addon files in the past several weeks.

Thanks for the response I will keep an eye on it I suppose!