So sorry for whats happened to you,i could reccomend to you TO NOT PRESS IT NEVER........................
leave it in powder or small chunks its the best way for enjoy your own/homemade RESIN in my book,
talking about your problem.................unfortunally mold its a part of your bubble,its not impurity or dirt on resin,with a not clean product you can do "THE PURIFICATION" hot water,hash'chunks in it,leave it for some mins,and you can SEE and SMELL all the SHIT IN IT!
but with mold this way not work at all,never ever had mold on my buble,just used to make it some mold'buds from the out and in this case you can stay safe,cuz mold stay away from your final product............
probably the freezer 'way its the only way,
here you can see ALOTS of RESIN pressed,
http://www.youtube.com/watch?v=I6SX-XWDUKo
sorry to say but for me its a great mistake press it,i like to think that
RESIN LIKE THE AIR
JUST LIKE CANNABIS ROOTS
sorry again for your stuff and keep posted about your attemps,can definetly help!