I make 2 Page in MasterDetial Page by imitating @JamesMontemagno 's Hanselman.Forms.
Each Page would pull data from Internet and Display it.
Assume "A" is the first Page, "B" is the second Page.
When I test the issue with slow network, "A", "B" Page pull the data at the same time.
Let app stays "B" Page, after seconds, "A" Page's data has finished so ready to display, It will crash.
Anyone has met it Or has some idea???