Vista system IE protection mode

        I don't know how many users are using Vista?
Vista protection mode
In recent days, IE has seen a new development under the embrace of Vista, with a protection mode. (internet option -> security -> enable protected mode)
This mode uses my understanding that IE forms with different "security levels" are not allowed in an IE process.
First explain here what is different "security level", maybe everyone's understanding is different - for example, trust sites and ordinary sites are not a security level.
Crashing problems
Hey... what's the problem with that?
A domain that joins a trusted site, such as a.site.com. A normal site b.site.com.
When you open an IE process and open b.site.com, this time you enter a.site.com in the URL (or have a link chain to a.site.com), you may not be able to open a.site properly. .com, or the prompt about:protectedmodeoff.
Solutions?
With such a problem, the solution is to first add a.site.com and b.site.com to the same security level. However, the standard is not a standard, unless you are using the internal network, if it is used on the Internet, it is not feasible.
Server Transfer~
There are no more examples of solutions.