UPDATE: There is a workaround to the problem. It is to force IE10 into compatibility mode by including one of the following meta tags:
I solved the problem in a very easy way. I Wrote a javascript code at the end of the page (or after the object tag in where is your silverlight app) and set the focus to another element, for example, a link. Example:
The shc var is useless, I put just for clarify. Remember: your javascript code must set the focus to another (but focusable) object AFTER the silverlight app object tag was parsed, which means your js code is writen after silverlight app object.