Recalculating (about every 1 or 2 kilometers)

Sometimes it can be a simple change to the highway such as 2 lanes to four or of such.

[edit] I'm gonna leave my original comments below BUT.....if you didn't check and find poor satelite reception during that time.....it might be some other "quirk" as mentioned in the other answer just before my post.
The following only applies if the sat. signal/lock was the cause of the problem.

There is another thread on here about interference from a proposed "new" use of a nearby frequency band.......in the US at least.

I think you should report your experience to whatever agency regulates radio spectrum useage.
Down here it's the FCC.
There could be some malfunctioning equipement in that tower.

It would be best if you could duplicate the problem before reporting it.

Do you have the latest maps?

I have 2011 maps ,but it did it when i had 2009 maps also.This is the only place it has ever done this . After i go about 10 km. everything is normal no more glitch's,When it recalculating the time to destination flashes and Jill recalculates every 1 km.then stops and she is happy again.She can be strange.She has always been accurate.

Any military bases around there? Just a thought.

I have had similar issues at times... VERY annoying!

I had the exact same thing happen to me with several different mapsets at the same location on the 595W in Florida and advised NAVTEQ. I submitted the report in November 2010 and it was resolved in February 2011.

It could be as you say some sort of interference but it can also be a problem with the map itself.

http://mapreporter.navteq.com/dur-web-external/secured/submi...

Is it possible to travel throught the area with out navigating and with the GPS in "Off Road" mode? Then upload the track coordinates to your PC and verify them against any other online map programs. Just a thought.

If all of the online map programs show your coordinates off the road then it could be likely that something is altering the GPS reception. If the coordinates are on the road on the online maps then it could be the installed map is incorrect. It might give you a clue one way or another.

No military bases so I will just stop the Jill part and just view the map then turn on my destination again after I get past it. Thanks for all your inputs.

@coonhunter: I've had various recalculating issues along the 401 and 427 in the GTA ans QEW near Hamilton, but never (well, so far so good) along Hwy 9

These issues have come and gone depending on the map version and sometimes were due to construction. Perhaps that Orangeville section of Hwy 9 is incorrect. Does it stop recalculating by the time you got to Hwy 25?

I was driving down the PA turnpike today through a construction zone where the lanes were shifted way to the side. When I would pass over or under a crossing road the GPS would start recalculating and momentarily throw my route onto the crossing road and then again recalculate moments later and move my route back to the turnpike.

Don't Worry, I didn't make any quick turns!

I have similar problem coming down I-95 South.Crossing into SC at South of the boarder.At least three map changes has not fixed it.Garmin was looking into the problem.Hoping the last map update fixed it.