When running top with Dual CPU's (XEON in this case) and the
idle cpu value approaches 0, the value will randomly go from
0.x to a value with more than 6 digits. I have never seen
this on single cpu systems, nor with RHL 5.2 dual.
This is probably because the ticks/second variable is (wrongly!)
summed across all multi-processors. There's a "qick fix" for
this in the Raw Hide procps-2.0.2-3.src.rpm packages, and a new
release of procps is planned in the next couple of weeks.
Please reopen this bug if the above analysis is incorrect.