What was used to plan the route?
Did you upload the "track" file?
What maps are installed on the device?
Was "recalculate" on (it shouldn't be)?
Are you saving the data to the sd card (seems to be preferrable)?

The frequent "freezing" is odd. The Garmins can freeze on long rides related to data collection and the size of the data/fit file but that issue seems to appear around 180+ miles (that is, it doesn't explain the earlier freezes). People recommend closing the data collection and restarting it (so a new file is used).

What did the screen look like when it sent you the wrong way? Was it a little blue arrow? Or a big white arrow?

The map displays the track route. It also displays a calculated course route. (Yes, there are two lines.)

Usually, these are on the same path (usually, they look like one line). When things aren't working quite right, the track route is what you need to pay attention to (the device needs to be displaying the map to be able to do that).

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There are three navigation modes (it's more like 2 and a half).

* The first (more basic) is track following: that entails keeping the blue arrow (representing your position) on the black-bordered purple line.

This method doesn't require maps at all. It just uses the current GPS coordinate to "draw over" the GPS coordinates displayed as the track.

The "off course" warning (it's part of this method) occurs when the current GPS coordinate is too far away from the track course (about 100 feet). It also occurs when the device doesn't get or loses the GPS signal (for example, when in a tunnel). It can also occur because the track coordinates don't quite follow the actual real-world position of the road.

If you get the "off course" warning, the first thing you should do is be aware that you might have lost a GPS signal and the second thing you should do is look the map screen to verify that you are basically following the track. If you are "far away" from the track (and going off in a different direction), you are almost certainly off course!

* The second is using what Garmin calls "course points".

This method is related to the first (and doesn't require maps either). These are a list of GPS coordinates with names and icons (little blue arrows, usually). When you arrive at a coordinate that has a "course point", the Garmin displays the name and icon on the screen. There are a few problems with this method. They are displayed at the turn, by default, which is, often, too late. They have a narrow "window" in which they are displayed. Alos, due to map/real-world differences and GPS "error", they can even be displayed after the turn. And, since they are just labels, they might just be wrong.

* The third is using a calculated route.

This mode is the one familiar to users of car navigation systems. This mode requires maps with routing data. The Garmin fits the loaded route to the nearest roads to calculate a separate route. Ideally, this will be the same path as the track route but a few things can cause the two routes to differ. The usual cause for the differences is planning the route using maps that are different than the map on the device. If you get wacky directions from the calculated routing, use the first method to confirm it.

The first method is going to be the most reliable. But since it's just a list of GPS coordinates, it might not follow the real road exactly (that depends on how accurate the map used to draw the track is).

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Read my prior post. It's important stuff to understand to be able to get the most out of the unit.

If you are using a calculated route ("Turn guidance on"), you will get turn annoucements at 0.1 mile to 500 feet before the turn. You need to use a "good quality" track route for the calculated routing to work well (and make sure "recalculate" is off).

You will also see a big white arrow on the map on the turn well-before you get to the turn.

If you are going fast (20+ mph), it's fairly easy to blow-by the turn (the 0.1 mile distance isn't really enough for high speeds), which is o ne reason you want to display (and look at) the map (like before you hit a down hill). If you blow the turn, the "off course" warning should sound.

I usually split long routes into shorter segments. That makes it easier/faster to restart the route if the thing gets confused.

Note that ugly things happen when recording for long rides (at around 180 miles or so). You probably want to make a habit of resetting data recording to use a new file at "standard" points during the ride. (Of course, that means the total time/distance is reset too.)

It takes a bit of practice/experience but you don't need a cue-sheet at all.

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"Tcx" and "gpx" are formats for files (both are "xml" formats). They don't describe what sort of data they contain.

Whatever format you use, what you want is a "track", which is many GPS coordinates that accurately follows all the turns and curves of the course. (Tcx files can also contain "course points.)

Historically, track data was obtained by recording GPS coordinates while moving. That data can be a bit messy.

Route planners (like ridewithpgs) basically produce a clean "synthetic" track, which follows the roads on a map. You can use a recorded track for navigation but it tends not to work that well.

Devoting time focused on learning/experiencing how the thing works is a good idea. Not enough people do that.

I suspect many people think that using them is (or should be) "easy". The reality is that they are fairly subtle and complicated devices. It takes some practice/experience/knowledge to use them well. There are quite a lot of people who have the units but don't use them for navigation (and get lost)!

If you understand what these are and how they work, you will learn to evaluate whether they make sense or not. You will get them when you lose GPS signal or if the real road deviates too far from the track (based on map data).

They do occur at points where they very-much matter but they are basically a secondary "fail safe" (like when you've blown a turn). Looking at the map (even before-hand) or when the warning occurs is usually enough to make sense of them.

You will quckling smooth over those rough edges (pun?). One approach is to charge it (top it off) earlier (during the day, when it isn't raining). That way, if conditions become less favorable, you are already set.

I said you won't need to follow a cue-sheet. Carry it or use it (too), if you like!

Realizing that you don't need a cue-sheet is kind of key to learning how to use the device.