Nothing changed in the drivers, or even most of the OS. It is highly unlikely the problem was related to the update, and might have been from the reboot.
That said, the configuration format of both 2.3.3 and 2.3.3-p1 is the same. Backup the configuration, reinstall from a 2.3.3 install disk, then restore the configuration. I'd use that as a last resort since it's likely a red herring and not the true source of the problem.
Before doing that, I'd try the usual things like swapping cables and trying different switch ports, etc.