Chinese charactors become '??' in exported excel

[#1]

Hi All,

     Sometimes i export data to excel, all the chinese charactor become '??' while other English words are shown what they should be.

It does not happen all the time. It happened mostly when there are too many rows contained in the tables which i want to export data from.

Is this issue caused by the excel or low memory? How should i avoid this?

Thankss in advance.