I've come a cross with funky problem with self signed PS1. I have signed scripts and they have worked well on our PCs.
Now I have one script which installs an application. I did sign the scripts and everything works smoothly on some of our PCs and it fails on others. We have language customization on our PCs and I've identified that system locale breaks running the script.
ee-EE, lv-LV, lt-LT and ru-RU are at least the ones where it does not work, but everything is OK in fi-FI, se-SE, no-NO.
If the script is not signed and I set execution policy to unrestricted, then the installation works.
Also if I change system locale and reboot PC then the signed script works.