HP-41C weird program behaviour

[rprosperi]

If that program will not run, entered after a reset, then there is definitely some kind of hardware issue with the machine.

Remove the batteries
Short the outermost 2 battery contacts
Press [ON] and toggle a few times
Let it sit with no power for 24 hours

Then put batteries back in, do a RESET ([<-]+[ON]), enter only that program, [GTO] [ . ] [ . ] to pack and then run it. If the problem remains, you need some h/w repairs, and I'm afraid I am not the right guy to tell you what part(s) may be the cause.

Good luck and please report results.