I ran into the annoying Could not complete the operation due to error 80020101 bug today. I clearly am not the only one (Google: Could not complete the operation due to error 80020101). This was an old bug in jQuery that was squashed and apparently is back in jQuery 1.7.2 except it isn’t back.
The original bug was related to HTML comments. This was not the cause in my case. It was a query string variable. The fix is simple, take out the query string from the URL.

Change it from this

to this

EDIT: Alternate Solution

Bruno commented below he this fix was not applicable in his situation. In his case, he needs the querystring. To that end, here is a way to eliminate the issue with a little bit of JavaScript.

You can leave the query string intact and remove it from the webservice URL before making the webservice call with a little bit of javascript. Before calling the webservice, use the following JavaScript to clean the URL and prevent the error

Voilà!
No more Could not complete the operation due to error 80020101