Thinking more about this the "~" will not do you any good. Still need to re-write the array but...

Assume file names should only contain letters and numbers. The problem is other characters are showing up..
So when the file name is read from the VDIP say it is saved into "arrayF". Before "arrayF" is used again it needs checked for bad characters. Right?

Again have a working array that will be used and/or reused to send back to the VDIP, "arrayW".

The bad characters are at the end of the name?
What if you check each bit of "arrayF" and IF the bit equals A-Z or 0-9 then that bit will be written to "arrayW". When the first bad character bit is found the re-write loop stops.
Now "arrayW" should only contain valid characters.

This thread should give you some ideas on how to process the arrays.
http://www.picbasic.co.uk/forum/showthread.php?t=8876

I hope this is on the correct track.