I've gotten the weird messages also, although not very often.
One thing that has always been a minor issue with me on this site (using two different computers running WinXP and Vista over the last couple years) is that about one time out of 5 the page will hang up for 30 seconds before fully loading. The one item that seems to hang up is the paypal image at the bottom of the page. This is an issue only because I will open the page, begin reading and scrolling down,and when the page finally finishes loading 30 seconds later it jerks back up to the original starting point.
I am not mentioning this to whine. I'm only mentioning this as someplace to begin looking in order to find the original problem with the database. This issue has been around for as long as this site has been on vBulletin (or shortly thereafter).