PI v1.8 RC3 Win7 64-bit...
The Process Console often comes up without the thumb slider on the right side of the dialog window, even though there's clearly more than one screen full of strings to review... when this happens, I grab the bottom right corner of the PC dialog window, drag it in any direction a pixel or two, then let it go. The thumb re-appears and functions as usual.
More annoying than anything, and certainly not a show stopper, but a bug is a bug.
Rod