a terrible weekend. need advice. Urgent

This long weekend is completely ruined. First off, big boss wanted me to work to meet a stringent deadline. this was not the worst though
Then I found out a discrepancy in data from one of our collaborators. Geez!!!! at the last moment when we are ready to present to sr management! I asked them for an explanation. They did not offer any. What should I do?

Here is my plan:

Talk with my boss next Monday and see if we want to completely stop the whole thing until we sort the issue out. But at this point, still send materials as-is out for review.

Any other suggestions?