[MiKTeX] \leftarrow display problem

[Peter V. <pet...@gm...>]

Hello,

I just installed the full package of MikTex 2.7 downloaded on 6 July 2009.

I use Winedt 5.6 and Windows XP to compile my latex document. However, 
after I use "dvi2pdf" function to convert the output to pdf, all the 
$\leftarrow$ notations disappear.

I try to do the above thing on MikTex 2.5, but in this case, no problem 
is found and all the $\leftarrow$ notations can be displayed properly.

Could someone give me advice how to solve this problem?

Thanks so much and looking forward to your reply.

Peter