i sometimes have the same issue! delete gaia and install lastest version
shut down playstation
load it bk up without hacking
then shut it down again
^^ (thats so you get a clean shut down and reboot from them 2 steps- helps ps3 as in certain situations the hack wont succeed unless i do this when have to force shut down from crashing etc)
then load bk up using hack and try again
also make sure diskless and direct boot are turned offf before you press a X on a game in gaia manager just to double check!
hope this helps mate.