BIS screwed up

For some reason, I cannot erase some of the files in my device even though I've tried a hard reset/soft reset/rom update (to flash the internal rom in hopes of "erasing" the BIS) and, still I can't get rid of the files. Is there any tool that can format built-in storage flash memory? Thanks in advance.

[cwsmith68]

Resco File Explorer gives the option to format BIS, but I havent tried it.

I tried that - it didn't work - says that the BIS is locked.

status update: upgrading to wm2003 right now... let's see if it does clear out the flash rom :)

status update: after the upgrade, it does not clear the BIS at all, but luckily, i can now delete the files.