Hi Sam
"Do you mean the zoom slider on the left of the scroll bar? I can't get this to happen."
Yes...I can zoom with the mouse wheel until the slider reaches the extreme RH end where it stops but I can continue to zoom in further with the wheel.
If I choose to click the + for move the slider then it will move to the right right in steps until it reaches the end where it stops but I can continue to zoom by clicking the + another 5-6 times. Seems the slider bar is too short. 
How would I "resync" it...and, yes, it's always been like that.
(Note: I don't normally zoom in so much,Mainly just enough to reveal and isolate sound peaks when I need to match sound tracks. In this case it was Lou's post that intrigued me and I wanted to see what size his clip bits were and why he couldn't find them on the timeline. As I discovered, at maximum slider position, obtained by using the slider; no use of the mouse or + button clicks, they only appeared as a blue line)
"VideoPad generates a frame for every 0.04 sec (25 fps) while editing. We allow the cursor be moved in between frames because conceptually the time line is continuous(each step is 0.001 sec). i.e. The frame position will change if the frame rate is changed(when export), but the operation (split, insert etc.) position on the timeline will not change. "
Having used VP a great deal I was already aware of the 25fps the program uses during editing as I sometimes shoot at 60fps and wondered where the extra frames went to. and although I mentioned in my post that I could shorten a clip to 0.001 sec duration by entering the value when in storyboard mode, the shortest I could get in my test above by splitting was 0.002 sec.
But, as you point out though, this was to the left of the join. Following your post I can confirm that to the right of the join it will split at 0.001 seconds. It's all academic anyway I think and if it's a bug I don't think it's a very important one. 
I'm more interested to find out how Lou generated them during normal editing.
Nat