I haven't run into this before, but perhaps someone else has. I'm consulting on a site with multi languages that uses the variable name "LANG" in the URL.
This results in URLs like
Both Google and Yahoo are caching these URLs to read
Now, I understand that ⟨ is html code for the less than sign that is appearing, but the URL is not terminating with a semi-colon, so I find it more than a little strange. The fact that both Y and G are misinterpreting it is even stranger.
I suppose I could recommend changing the language variable name, but is there a more elegant solution that wouldn't require a back-end change and the complications that come with it?
This is why the ampersands in all variables in URL links must be encoded as
& - in most cases the browser (or SE bot) can handle unescaped ampersands, but not always.
So you need to modify your code to use
& in on-page links (ie. in the HTML) at all times: example.com/blah.php?arg1=34[b]&lang=eng[/b]
The W3C validator will show the unescaped ampersands as errors if you validate the generated page. This is actually a good example which shows that search engine bots really do respect standards and prefer valid HTML. :)