I've used MM4 for the longest time, and I've had mm6 and never installed it.
This weekend I installed it and noticed that from mm4 to mm6 the BPM's are high...and I mean REALLY HIGH.
Example:

mm6: Brass in My Pocket - 197.2
mm4: Brass in My Pocket - 98.5

I have not read any other help on the reason for this....does anybody know how to fix this?

Right-click track, choose properties. On the Window there will be a secction bout BPM which includes the ability to set it as 1/2 times (e.g., cut the BPM in half) or 2 times (double it) or tap it out.

Why does the BPM go that high?

I guess its something I need to learn from version 4?

The Help file doesn't really go into that detail ... in v.7, the Help says "It could happen that the tempo for your track sounds way off. This might happen if it's a live recording or the track has a lot of solo vocals." I'm sure there must be other reasons, but it's a question you'd have to ask the developers, I guess....