Hi Alex,
Unfortunately, the current version 1.6.1 of PixInsight for 32-bit Linux does not work well. This is due to a mistake I made when I compiled the core executable. PI 1.6.1 works perfectly on 64-bit Linux distributions as well as on the rest of platforms (FreeBSD, Mac OS X and Windows, both 32-bit and 64-bit versions).
The new version 1.6.9 fixes all of these problems. The release is imminent, so I just ask for a bit of patience. In the meanwhile you may try to install PI on a 64-bit Linux distro if you can (you have to move your license file to your home directory on the 64-bit machine, or email us and we'll reset your trial license).
Sorry for the inconvenience.
Edit: I forgot to say that we'll restart all trial licenses for 32-bit Linux users as soon as we release PI 1.6.9. In this way they'll have the whole trial period of 45 days.