So far I had always tried the wizard first. This leads to the state I described before, where the interface is basically dead.
Now finally I tried to load a style before I did this and voila, I was able to load it, load a player and even a kit. So it seems that the wizard is killing my interface somehow.
It worked for a while, although things were still a bit weird in that after loading another style, the accent and fill pages were suddenly blank.
I then tried the wizard and got an "Access violation at address 0000000300000003. Write of address 0000000300000003"
Jamstix 3.5 B6 was dead then, I tried to load something else and got an "Access violation at address 000000001AB3123B in module 'js3sl64.rtxc. Read of Address FFFFFFFFFFFFFFFF."
S1 didn't crash, but whatever I did I got different such messages.
Seemed pretty borked
After reloading S1 (this time with Admin privileges which doesn't seem to matter though) I played around some more and while it feels flakey and I got some more Access violations, I was able to load stuff and try some things, as long as I don't touch the wizard.
Regarding the Interface: Now with the new and more slick interface elements, the rotary dials look very aliased in comparison.
Cheers,
Tom