LPC1788 USB host controller

Dear friends,

I've got this weird problem with the USB controller on LPC1788. I use RL-USB to do the job. I initialize the RL-FlashFS file system on the USB and I create a text file and simply write "Hello World!" in this text file using fputs function.
This is the main function of my application:

int __test = 0x55;
int main()
{
        FILE* txtFile;
        __test = finit("U0:");
        if (__test)
                while(1);
        txtFile = fopen("U0:test1.txt", "w");
        if (txtFile != NULL)
                fputs("Hello World!", txtFile);
        fclose(txtFile);
        while(1)
                funinit("U0:");
}

so far so good. Everything works fine, the file is created and the string is written to it (I see it in the debugger). The strange thing is that when I connect the flash memory to my computer, there is no such a text filet as test1.txt in it.

Even stranger is that when I reconnect this flash memory to my own hardware and try to read test1.txt, using fgetc() function, it is read just fine and the string "Hello World!" is returned.

I really have no idea what is going on. If you have any experiences about this please share it with me.

Regards