IE has a Lookahead Pre-parser. If your is not organized in the correct order your will get restarts in IE.
For example you interleave CSS and JS links. All CSS should be positioned before any JS links.
Your last CSS is loaded in Request #35. The Start Render does not begin until right after this request.
As far as the Request Canceled it may be due to Request #9. #9 is a CSS following 5 subsequent JS links.
Yahoo best practices says: The problem with putting stylesheets near the bottom of the document is that it prohibits progressive rendering in many browsers, including Internet Explorer. These browsers block rendering to avoid having to redraw elements of the page if their styles change. The user is stuck viewing a blank white page. (From: http://developer.yahoo.com/performance/rules.html)
Regarding the IE re-start:
While WPT did not find any 404 page not found W3C mobileOK found 4 (may have to do with mobile User Agent) :
Triggered by http://m.fiatprofessional.it/fiatpro/img/arrow_dealer.png.
Triggered by http://m.fiatprofessional.it/fiatpro/img/bg_btn_gen.png.
Triggered by http://m.fiatprofessional.it/fiatpro/img/btn_menu1.png.
Triggered by http://m.fiatprofessional.it/fiatpro/img/linea_sfumata_header.png.
Triggered by http://m.fiatprofessional.it/fiatpro/img/piu.png.
DNS resolution issue: http://m.fiatprofessional.it/it-it/prontaConsegna.
39 HTML Errors:
Most of the errors appear to be doctype issues. /> the slash a the end of a shorttag is a XHTML and creates an “error”.
Testing your page with an HTML5 doctype produces errors related to obsolete attributes used in table elements.
I prefer using the shorttag slash and closing tags and never use an HTML 4.01 doctype. I always use strict rather than traditional. Use the W3C HTML Markup Validator’s “More Options” to override the doctype to see which works best for you.
While your server is blazing fast at 10-20 MBytes/sec the TTFB is rather dismal. May be related to ASP.NET.
You need to work on the First View VisualProgress. Getting a blank screen for 5-6 Seconds is going to lose a lot of first time visitors. Move all the CSS to near the top of the HEAD preferably in a single file. Move as much javaSript to the bottom of the body. This will allow the Start Render happen sooner.
For me, the instant I hear unexpected audio, like from your video, I can’t find the Back button fast enough. My PC is connected to a 400 Watt per channel Amplifier. Even if the user backs out momentarily to turn down the volume it is still perceived by Google to be a bounce lowering your ranking.