I have a issue when after opening my qlikview file with browser from the server it is loading without any problem but after opening it from other client(phone, laptop) it stuck on blank tabs. Then I check server's Task Manager and CPU usage is on 100%. Even after closing browser from the device I was trying to view file from, cpu usage is stuck on 100% and I must restart the QlikView service to take it back to normal stages.
My qlikview files isn't really complex biggest table is with 2m records.
What is the QlikView server log files tell you? Have a look at the performance and event log to see if you have any vital information there. I would also recommend that you bump up the logging to high if that not already is the case, to be able to see if that presents any more clues next time you are experiencing the same issue.
Would also be of interest to know if you using the same client on all of the cases (AJAX i assume as you talking about using a phone) or are you in some of the scenarios using the plugin?