a signal 11 basically means that the process accessed, or tried to access,
memory that it had no access to, either because the address didn't exist in
its address space or because it didn't have the right permissions.
you could try to run a some sort of memory tester and do that check, or it could be do to malfunctioning hardware, or simply the package for qtella could be corrupted, so for simplicity reason maybe just try removing what you do have related to qtella on your box, and re-download it from a different source ..
you can look at this link
just to get more of an idea on what a signal 11 is related to ..
this is a faq about receiving the error during a kerenl compile, but just read the answers to the questions and you'll see what could lead to a potential resolvment in your case ... and plus you will pick up things that you didn't know about it ...