Focus assist feature on the 170

Has anyone experienced problems using the focus assist function on the 170 (1)? 99% of the time I use Manual Focus but have had the Focus assist feature turned on. That gives me a shorter throw on the focus ring and is meant to "touch up" focus in run and gun situations. I have found that at times though it throws the image out of focus if the background is particularly complex. As if the auto focus feature was turned on. The sad thing is since the viewfinder resolution is not the greatest, at times it's not that noticable, until viewed on a regular monitor. And I'm only talking SD, not HD. I called Panasonic but they have no idea what could be going on if the 2 switches on the camera body were flipped to manual. The only thing that I came up with was what I mentioned about the Focus Assist function that I found in the Barry Green "bible" (page 141). Just thought I'd thow it out there to see if anyone else had run across a similar problem.

Dual 2.7 GHz G5, 4GB RAM, ATI Radeon 9650, Xserve RAID, AJA IO, 2 20" Cinema Display, FCP Studio 2 (6.02), OS X10.4.11