yah, its got me too. started a few days ago. i upgraded to 3.5 about a month ago. possibly related. anyway, i find this at:
http://code.google.com/apis/gears/gears_faq.html#linuxCompatible ------ What does Gears require to be compatible with my Linux system? If you'd like to run the Gears for Firefox on a Linux (32-bit) platform, please make sure your system has glibc 2.3.5 or higher and libstdc++6 (Gears 0.3) or libstdc++5 (Gears pre-0.3). -------- OK. i've got libstdc++6 installed, but glibc? searching for glibc my package manager shows only glibc-doc and glibc-source. maybe they mean libc6? (mine is at 2.7-10) described as the GNU C Library: Shared Libraries. also http://packages.ubuntu.com/source/hardy/glibc (for instance) shows libc as the GNU C Library: Shared libraries In any case, I still get the error.
