... seem to be able to fire up Templot and make a change to the track spacing by moving the slider and accepting the value but if I dither around on the slider moving it around for a short while I get an error from Windows. Have tried to upload screen shots but Templot Club just sits there. First screenshot attached also noticed the PC CPU use spike just as the crash occurs- see next post for the screenshot. Sorry in a bit of a rush- supposed to be cooking the evening meal Rob Attachment: attach_3091_3699_Crash_Monday.jpg 157 posted: 15 Jun 2020 22:21 from: Rob Manchester...2nd screenshot attached. Rob Attachment: attach_3092_3699_Crash_Monday_- _cpu_use.jpg 144 posted: 16 Jun 2020 03:54 from: Martin Wynne Hi Rob, Thanks for reporting this. I can see in the code the possibility exists for a race condition, I will have a think about how best to prevent that. On the other hand, I can't actually reproduce the problem here, on several systems. It is also exactly the same code ...