I don't use Draw Marks, but I would guess David is right in that there must be a macro or custom shortcut that is triggering it to turn off as I don't think there is a INI setting to turn it off. The only thing I can suggest is since you said it happens so freaquently is to slow down a bit and notice when it stops displaying and see if you can figure out what sequence of tasks/commands/quickkey shortcut/macro triggers it to happen. Since it's something that happens on screen it should be pretty easy to notice when it happens. If you think it might help, you could set up a camera or on-screen recorder to record a work session in case you think you can't catch it yourself quick enough so you can go back and replay when it happens. I use
Faststone Capture for simple screen captures. It's shareware that has a free 30 day trial that should give you enought time to hunt it down.
If you find something else out, report back with the new info and maybe we can help get you fixed up.