1) it looks like a custom error message. Possibly why research turned up nothing.
2) shift bypass might be disabled. If you research it, you can find a way to allow it. I would do it for you if you post a db copy but I'm not going to publicize how as it's one of those things that shouldn't be known by everyone. Sounds odd no doubt, given that you can find code for this, but for me it's like a hacker thing.
You didn't say if the problem pc's have a different date format setting than the one that it opens on. If the db is checking date format in regional settings and throwing up a roadblock that's an odd approach but I guess it was easier than other methods.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.