TicTac,
Do you mean that the physical machine is going to be replaced or are we getting a different mysql version?
Another thing that could be the problem is that they are using Windows 2000 and not Linux, like I use at home to test forum changes on. Of course I don't get anywhere near the load our web hosting provider does, having tested on Linux and Windows at home I think Linux is the better choice for http, mysql, and PHP services.
That's just my opinion and I have no facts to back it up. Windows just seems less reliable for server functions to me.