could be that Mint has not installed that driver by default, you could try to install broadcom-sta-common from synaptic, if it's not already installed. if that doesn't help, maybe it was fixed in an update, which Mint is holding back (they are holding back updates for critical components like drivers and kernel, so they don't mess up working systems), so the next thing I'd try would be updating to the latest Ubuntu packages, using the command line
sudo apt-get update
sudo apt-get dist-upgrade
don't get discouraged yet, there's still hope

“A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila” (Mitch Ratcliffe)