Firmware update can solve uploading problems on Arduino BT ??

Hi everyone, I have a arduino bt (atmega168) and I run it on windows 7 ( 64 bit). Two months ago arduino suddenly stopped uploading sketches. I Tried to solve the problem with many different ways: 1) I install arduino IDE on windows xp, vista, 7 and ubuntu 10.10 2) I updated the java with latest version. but the problem still exist. I can't upload skectes, because Arduino IDE didn't allow me to choose properly seria port. I read a post at furom for firmware updated for uno. Here is my question: can I update firmware at arduino bt and how. On the other hand any possible solutions..?

P.S. I run a deadline project and I was working with arduino bt (win xp, 32 bit) for 5 months every day,but after a format stop to work.

Thanks, MikeLe