Access 2003 - Won't Debug

[Michael]

When I run Access on my desktop, I seem to lose the ability to use any debug
facilities.

All "stop"s in the code are ignored.

I F9 a line - the "brown dot" is shown, but the stop (or the word Stop) are
ignored.

However the same code when run on any other computer allows breaks.

Have I set an option to stop debugging?

TIA
Michael