Greetings! Since firmware 1.4 I have an issue with USB HDD - it started only on USB 2.0 after reboot, but since 1.5 it is on all ports - I need to replug the the HDD after every reboot or player does not see it.
It probably needs a cleanup; nasty but known to happen with all Android players. Factory reset and/or Emergency Firmware reload.
On mine an USB pendrive left connected was seen after every poweroff - poweron, indeed in a annoying way because Media Center choosed it as startup path even not in preferred. But maybe pendrive have a different behaviour compared to HDD.