GPS turns on and goes to warning screen and freezes.

Called tech support as I had the same issue. Slide the power button over (to turn off). Hold for about 15 seconds. Wait a few minutes after u release the button and then restart. It should be ok after that

These units are prone to freezing on occasion. There likely isn't anything wrong with the unit, just a certain set of particular circumstances caused the software to lock up. Turn it off completely let it sit for a minute and restart it.
If you continually have this problem in the same menu, doing the same thing, I'd recommend updating or reinstalling the software onto the gps unit by following the directions that come with it.

have you tried resetting the gps system with the reset button?

What happens after that screen is that the operating system is loading, I would say that the software is corrupt. Garmin will be able to walk you through reloading the software.

I can help you reset and fix your Garmin Nuvi 265W.

Getting stuck on the flashing Garmin logo, or a message about not finding any maps, or freezing and rebooting, are indications that the firmware / system software inside your GPS has been corrupted.

There are three steps to take to get your Nuvi 265W running like new:

1. Back up your Favorites.
2. Perform a Hard Reset.
3. Download and then run Garmin WebUpdater to replace its firmware / system software.

I hope that helps.
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Nuvi 265W Manuals here.

Try update the unit with the latest firmware by using WebUpdater from Garmin. 

There are three levels of fixes, please try them in order:
1. Reset the GPS using the Reset button, on the back, just under the Antenna Hinge. Resetting will turn off the GPS, and then turn it back on, if connected to power. Test, if fixed, great, otherwise, go to fix 2.
2. Turn the power off, then press and hold the powerbutton for up to 2 minutes. The GPS will turn on, and display a "PreBoot Mode" message. When that message disappears, and the screen calibration screen appears, follow the on-screen instructions, and you are fixed. If you still cannot use the touch screen, repeat fixes 1 and 2 several times, just to be sure., then go to fix 3
3. The touch-screen glass has probably broken or lost its connection with the GPX motherboard. You can order new touch screen glass on the web and install yourself, if you are techy in nature, otherwise do a search for "garmin nuvi 660 repair" and choose your service.

pin the reset button at the back

If you have a memory card inserted, remove it...if the problem goes away, try replacing that card. If the problem occurs with any card then...

Try installing the latest update from http://www.lowrance.com/en/Downloads/Product-Software-Updates/
even if you already had the latest...try installing it again.

If the problem occurs with any card, and after updating or attempting to update, there is a probably a malfunction with the XOG and it will need to be repaired/replaced. The Lowrance contact by phone is 800-324-1356 and go to http://www.lowrance.com/en/Support/Product-Support/Contact/ to email them.

register your unit on the magellan website and there is a firmware update and it will solve your problem