How to correct Google Earth's "invalid HTTP request" notice?

This is due to an old libcurl version, that seems to cause the trouble. If you already have libcurl on your system (and I am pretty sure Ubuntu 12.04 has), you can simply rename the libcurl coming with Google Earth like this:

sudo mv /usr/lib/googleearth/libcurl.so.4 /usr/lib/googleearth/backup_libcurl.so.4

And the problem should be gone (the path in my Linux Mint and probably other distributions is /opt/google/earth/free/libcurl.so.4).

I suddenly started seeing this error after running several updates. I tried a number of things unsuccessfully and finally updated GE to 7.1 - it couldn't hurt. Problem went bye bye! I hope this works for you.