/usr/bin$ sudo ./ktorrent
Qt: Warning: X Error: BadDevice, invalid or uninitialized input device 158
Major opcode: 146
Minor opcode: 3
Resource id: 0x0
Qt: Warning: Failed to open device
Qt: Warning: X Error: BadDevice, invalid or uninitialized input device 158
Major opcode: 146
Minor opcode: 3
Resource id: 0x0
Qt: Warning: Failed to open device
ERROR: Communication problem with ktorrent, it probably crashed.

Funny problem. Ktorrent runs fine without sudo, except I need Ktorrent to listen on ports under 1024. Ktorrent runs fine under root, which is my solution to the problem, but it SHOULD also work using sudo.

OS: Ubuntu Gusty (7.10, Debian-based)
Qt: Version 4
X: Gnome2

The root account probably is not allowed to access the X server, so do this :

xhost +local:
sudo ktorrent

Btw, why do you need to run on a port below 1024 ?

The X is allowed in root because I can pull up a terminal in another user, su root, and then run Ktorrent without problems.

ISPs are getting bad about blocking torrents. I would recommend to those using an ISP that fits in this category to allow KTorrent to run on ports 22 and 443 with RC4 encryption so the data looks similar to SSH and SSL.