I had some similar problems with an nvidia dkms module not loading properly at boot. Lxdm would cut on and off, interrupting my command line until I sv stop lxdm the service and rebuilt the kernel module. This was gone over in the thread titled "Nvidia problem?". This may not be your issue, though, it would help to see the other logs from Xorg/X11 and possibly check dmesg or syslog files. Sorry if that's not very specific, log file names have changed since I took classes 10 years ago. It kind of sounds like X isn't up for lxdm to run in.