Montana 750i random freezes or powers off

You should probably open a support ticket. There have been multiple forum reports of the 7x0i powering down, freezing, or rebooting. Usually (although not exclusively) when subjected to a "rough ride". Sometimes connected to external power, sometimes not. 

I opened a support ticket as well. No response from Garmin, other than the canned ticket acknowledgment.

As an update, I did hear back from Garmin today. Their recommendation was to upgrade the software on the Montana from 8.5 to 9.2. 9.2 was released two days ago. I happened to be downloading tracks from the Montana, and upgraded the firmware to 9.2 a couple of days ago anyway. I checked out the bug fix list, and there are a few that may apply to this problem if you look at them sideways. I won't be able to do a repro of the scenario for a while to verify if this fixed my issues or not. Basically, I don't know if this is the old "upgrade your software, then see if the problem still repros.. as we don't want to fix potentially old bugs" or if this is actually fixed, and not in the list of specific fixes.. either scenario is plausible.

My husband is in the middle of Hudson straight in the Arctic and his brand new Montana700i keeps freezing. He is not using a mount .  Very annoying and unsafe in such area where he relies on this.  Will call tech support tomorrow morning again. Unfortunately he cannot try to update software in the middle of the ocean with no other connection.

I received my new 700i on August 6, 2021. It installed software updates that night. While hiking on August 7, 2021, with the 700i in my backpack bottle side pocket with the screen off, it became unresponsive. Pressed power button many times and screen would not turn back on. Held down power, nothing. Had to remove the battery and put it back in. Unit started back up and was still tracking my route and recorded my hike. Worked fine hiking on August 8, 2021, doing the same activities. Hopefully a one-off.

I have the 750i mounted in the 4wd using the suction mount.

When I turn car on it switches on and when I turn car off it powers down after 30 seconds.

But...

It sometimes does not power up again. I too have to remove the battery and put it back into mount and it works again as it should.

This happens at least once a week.

I hope the fix this as it does become annoying. 

So I've been having my 700i freeze every time I tried to look at a saved Activity. Found out that if I shut off the blue tooth connection to my phone, it didn't freeze anymore. Not sure if this will help anyone else, but may be worth a try. 

I had this happen two or three times in a row in the last week. I don’t think I want to turn off bluetooth but appreciate the info.

Even with the bugs I do love this device. I mainly bought it for the satellite capabilities but it can do so many things I didn’t even know I needed. Overkill for hiking but I don’t even mind the size. 

I had the same problem.  It would randomly lock up and I had to remove the battery. My solution was to log onto the preferences section in the baseCamp app.  Go to the advanced tab, and decrease the Disk Cache Size.  I set mine to 712 MB and I saw only a little decrease in performance.  You might be able to go higher but I am ok with my setting, My GPS software version is 2.8 and the Unit software version is 9.20