HP have also released a Customer Advisory c04302261 on the issue.
This was a tricky one to deal with, as one possible step might be to roll back/downgrade the driver to an earlier version. Unfortunately, not only is this not supported (or documented), but you might also find that an older driver may not work with a newer storage controller. The good news is that HP now have a new version of the driver available which fixes the issue. Customers should upgrade to HP Smart Array Controller Driver (hpsa) Version 126.96.36.199-1 (ESXi 5.0 and ESXi 5.1) or Version 188.8.131.52-1 (ESXi 5.5). Details on where to locate the driver and how to upgrade it are located in their advisory. Think about doing this as soon as possible.