- Some/all of the map tiles don't load
 - You can view road maps but not satellite maps
 - You are told there is no imagery for this zoom level, even when
zoomed all the way out

follow these steps:

Step 1) Are you using Firefox 3 and do you have Skype installed? If
so, remove the Skype extension. This is known to break Google Maps and
other websites.

Step 2) Check these help topics:

http://maps.google.com/support/bin/answer.py?answer=21849&topic=10789
http://maps.google.com/support/bin/answer.py?answer=18529&topic=10789

Step 3) Try loading a tile URL directly, by opening the following
links:

http://mt3.google.com/mt?n=404&v=w2.75&hl=en&x=7&y=12&zoom=12

You should see a roadmap for part of America.

http://kh0.google.com/kh?n=404&v=28&hl=en&t=t

You should see an image of the Earth from space.

If you see:

a) "Connection timed out" then try rebooting your router and trying
the tile URL again. Does that help? If so, you may need to reconfigure
your router to switch off its firewall.

b) A sorry message from Google, your IP address has been temporarily
blocked. This should only affect satellite view. The problem is caused
by usage of programs which are not produced by Google to access
satellite imagery. This can include a few websites that don't use the
official Maps API (eg, flashearth.com did this until very recently).
It is never caused by using Google Maps too much, despite what you may
read elsewhere on the internet.

c) Something else .... post your problem here and we'll try to help.