Uploaded font-file vanish

Hello!
I Has uploaded a font through WinBOX into RouterOS 6.37.4.
Through some time the font file is removed with RouterOS, sometimes vanishes at reset.
Does anyone have the solutions?
Thanks very much!

What device it was ?

I run X86 type ROS in my desktop computer.
I have try many v6.x versions, but all have the same problem.
Thanks your reply.