Pagelatch_ex, pagelatch_sh, pagelatch_up is related to pages stored in memory. If a user waits to access a page that is store in memory and he/she needs to wait on that page, then a pagelatch occurs.
This is not the same as pageIOlatch_xx.
What to do
Basically it is a very technical issue, and I would recommend that if this occurs, then you start writing to the SQLPowerhouse support, and then we can help you with this wait type.
However, you could start monitoring some of the performance counters that are related to PageLatch.