LinuxCNC not launching

My system is handing on launch. The Axis toolchanger appears briefly - as normal, but the main window doesn't appear. Re-launching doesn't work, the computer has to be rebooted. The rest of the OS works fine, but tit will not re-boot, it has to be powered off at the switch and re-started, as if it is being blocked by a process. 
Running Version 2.8, but have been using this system for around 10 years without a hitch until recently. 
It started off being an occasional random occurance, but now it seems permanent. Very frustrating.

Any suggestions welcome.

Thanks

Dave

pull the cards, sounds like a hardware issue

Thank you both for the replies. Well, I've had my money's worth from that old PC. At least 15 years old. I bought a newer PC and parallel port card a while back for this situation. Best dig it out, fire it up and check if the parallel port is compatible. Wish me luck!