I've been using this cool little tool lately to narrow in on some code problems:
http://validator.w3.org/
It's a nice way to find exactly where your errors are, (if any) and what you should do to fix them.
I found it interesting to check up on a few big names:
microsoft.com currently has 2 errors
msn.com passed with 0 errors
apple.com currently has 9 errors
google.com currently has 55 errors...
mozilla.com passed with 0 errors
myspace.com currently has 133 errors!
Microsoft and Mozilla win.
Of course ITforum.com currently has 45 errors.. (Booo!) but they are mostly stupid things like embedded tables.. hehe. I just started fixing this today though and I've knocked down quite a few errors so far.
Shooting for passing with 0 errors soon. 
http://validator.w3.org/
It's a nice way to find exactly where your errors are, (if any) and what you should do to fix them.
I found it interesting to check up on a few big names:
microsoft.com currently has 2 errors
msn.com passed with 0 errors
apple.com currently has 9 errors
google.com currently has 55 errors...
mozilla.com passed with 0 errors
myspace.com currently has 133 errors!
Microsoft and Mozilla win.
Of course ITforum.com currently has 45 errors.. (Booo!) but they are mostly stupid things like embedded tables.. hehe. I just started fixing this today though and I've knocked down quite a few errors so far.