Thank you for your posts, my apologies for a delayed response. You have driven me to do a full analysis of the problem which I should have done in the first place if I hadn't been convinced it was a problem with 256 Gosubs.
I now have a fuller understanding of the problem and I have a work-around, but not a fix. Just in case you are interested I will tell what I have found.
Firstly, when does it occur? Three actions can bring it on
1. Changing anything on the Options panel and pushing Apply.
2. Pushing OK with or without changing anything
3. When Cancel is pushed, it does not happen. But, if I subsequently close the
Program Editor and reopen it, it is immediately hung.
Once hung, I can close it by clicking the top, right-hand cancel button on the Options Panel or the main Program Editor screen. However, Windows cannot close it and produces an End Program - Programming Editor window with the options of End Now or Cancel. End Now closes the Program Editor. If it is subsequently reloaded, it is hung immediately. Only rebooting solves the problem.
The work-around I discovered accidentally, as usual.
When it is hung, without closing the Program Editor, I restart the computer. It closes down my MP3 player (which was loaded first) then displays a window End Program - Progedit.exe which has a growing bar and the words Ending program. Please wait. There is an End Now button.
If I close this window, not using the End Now button, Program Editor usually puts up a window saying Run time error '5' and closes. When I reload Program Editor I can change anything on the Options Panel and push any button I like. It never hangs. And, of course, I can compile a program with over 16 Gosubs.
However, after rebooting the computer the change problem is back, but at least it has loaded the options I entered while I could.
The problem is unlikely to be in your software but if you have any pointers on where to look I would appreciate them.
I have done nothing to the standard security nor loaded any but my standard software. The main software I use is the Program Editor, an AV package called Avira, a PCB design tool called Target, an old MP3 player called Xing and some solitaire type card games. I reloaded the OS and all my software in January this year. I don't download odd software, I have settled on my operating environment and stick with it.
Thanks very much for your help.