freezing SMS... ERRRR!!! Help please!

HELP!!!! PLEASE!!! ok so whenever my Boyfriend (who is stationed overseas, and this is our best way of communication) sends me a message through AIM and im not logged in it will send the message to my phone via a txt message... BUT... i will recieve the txt and i will select it to read it but the message will not show up untill my blacklight goes out then when i try to send a reply my blackberry completely freezes until the message has been sent... which seems to take a good 2-3 minutes. how can i fix this... whats going on... it only does it to the AIM messages (and right now my AIM wont let me sign on to my BB....saying that there is an internal error, that just started but the txt problem has always been) Any suggestions? any help is very aopreciated! thank you!!!