By default only one scheduled agent runs at a time on a database.
What do the server's Agent Managers say about what's running on this database?
Running agents every 10 minutes is bound to cause issues, but they don't cause this particular issue. Eventually though your admins will be annoyed. The schedule queue becomes useless with the agent queued up like this.
If it's just doing file operations, I'd probably suggest pushing it out to VBScript and schedule it in Windows. Because it doesn't seem to offer much use in Domino, based on its description.
People have replied with some good, plausible causes.
I've run into shared drive issues where due to network issues the OS will stop responding, freezing the agent. Net result: the agent stops running.
There can be lock-ups with multiple agents racing for the same file. E.g., a test & prod agent both looking for the same file, then one deletes it out from under the other. Or a separate agent running infrequently that locks up the file.
Does your server do design updates? An update could change the signatures on script libraries or it may have a later signature on the agent. Script libraries also have to be signed with sufficient access rights.
It may be worthwhile looking at the agent manager's queue to see if something else is gumming up the schedule queue. Is this agent truly falling off the queue?
Is the server or agent manager telling you it's falling behind? If it is, well, it is. In that case you'd need to reduce the runtime of the agent, because it's taking longer to run than the 10-minute interval given to it. e.g., 10 minutes when you're letting agents run for 15 minutes, means you could lap the server.